Artnautica 58—Design Analysis

LRC58 007 perspective views

In the last post, John’s talked about a new motor yacht design that’s quite different from just about anything you’ll find coming off a production line. We’ve had a flurry of comments, some supportive and some skeptical. Now it’s time to put our preconceptions aside for a moment and consider if, from a technical perspective, the boat is likely to work as expected.

Let’s start with the conclusion: The concept is sound, the numbers are sound, and I think designer Dennis Harjamaa will be very happy with the boat. If I were in the market for something six times bigger than the boat I’m building, to serve a similar mission, this would be near the top of the list.

How light is light?

As drawn, weighing in at just 12 tonnes for a 17.8 m overall length, the Artnautica LRC58 is light indeed. Just how light is this thing? Let’s compare it to a few other real and hypothetical boats we might be familiar with. The table below lists the traditional displacement/length ratio, or DLR ( in long tons / (0.01*ft)3), and the modern dimensionless version (LDR, also called the slenderness ratio).

Vessel DLR = D/(0.01L)3
LDR = L/D3
Morgan’s Cloud ~ 312 ~ 4.51
Adventure 40 ~ 200 ~ 5.23
Doral 19 runabout ~ 170 ~ 5.52
Dashew FPB64 ~ 150 ~ 5.75
Artnautica LRC58 ~ 65 ~ 7.6

In other words, the LRC58 is – relative to its length – dramatically lighter than a Dashew motoryacht, and an absolute featherweight compared to a ballasted sailing yacht like the proposed Adventure 40. It’s even lighter, in relative terms, than my parents’ high-performance 19 foot runabout.

The structural engineering will be a real challenge here. This is a very light boat that will require careful attention to weight and structural details to achieve her mission.

We can see this if we think of her weight breakdown in terms of fuel fraction and payload fraction. The larger these fractions are, the more challenging it will be to engineer and build it. They also tell us a lot about the trade-offs between range, efficiency and payload capacity that went into a design.

A reasonable estimate of the LRC58′s thirst in typical wave conditions would be a fuel burn of 7 to 8 litres per hour at an 8-knot cruise. Dennis’ site mentions 3800 L of fuel for a six thousand mile range (5.7 L/h, probably calculated at 6–7 knots). In other words, fully 25% of the boat is fuel – an unusually large figure that implies a serious long-range cruiser.

He’s planning to carry 2300 L of water and we would undoubtedly want at least 1500 kg for food, cargo and personal gear. That works out to a payload fraction of roughly 25%, leaving somewhere between 5.5 and 7 tons for the structure, interior and all mechanical systems. I think this is achievable but it will require discipline (can’t have any unnecessary junk on board), skilful engineering, and reduced margins for error requiring very thorough QC during the build.

For comparison, a Boeing 737 has a fuel fraction of 27% and a payload fraction of 13%. Trawler yachts usually have a fuel fraction in the 12–15% range, with payload fractions also being in the low teens. A Dashew FPB 64′s fuel fraction is roughly 29%, but those boats are 2.3 times heavier and a bit faster, relative to their length and accommodation volume, than Harjamaa’s design; not surprisingly, they also carry (at 12,800 L of diesel) about 3.4 times as much fuel to get a similar range. Long-range motoryachts are not the same kind of animal as their short-hop coastal cousins; pushing the fuel capacity out to trans-oceanic levels means that we’re approaching an airliner’s sensitivity to weight and its distribution.

Hull Details

LRC Lines Plan

The flat aft buttock lines will help the LRC58 generate some lift in the stern at speeds above eight or ten knots. It won’t quite plane with the specified 75 hp engine but it will lift a little, like a down-east lobsterboat, if pushed hard. Although I have not done detailed performance simulations on it, I would estimate that an efficient 8 to 9 knot cruise would be possible on about 40 horsepower; the 75 -horse diesel he’s planning to fit will be just about perfect. A hull like this doesn’t have a defined “hump speed” and so if you wanted to fit three or four hundred horses, she could probably reach the mid-teens without too much fuss. That would, however, rather defeat the intent of the boat.

An unusually fine bow, reminiscent of the wave-piercing patrol boats starting to show up in modern navies, leads into a gently rounded forebody. There’s enough deadrise here to ensure a comfortable landing when coming off a big wave. Farther aft, the bottom transitions to a flatter, harder-chined profile that provides much-needed initial stability to the relatively slender hull. With a length/beam ratio of 4.83, the Artnautica is rather on the skinny side compared to many motoryachts of similar size—a plus for efficiency and speed. A long skeg starts sweeping downward just aft of midships and, in the final two or three metres of the hull, the bottom is nearly flat with a slight tunnel along the centreline. The basic shapes of this area have been seen before, in the larger Sea Brights and in some Downeast lobster boats, so while Harjamaa has tuned and tweaked things a bit, there’s nothing radical or unpredictable here.

Harjamaa may have been inspired by the old Sea Bright skiffs and their rumrunner descendants in drawing the aft body, or this could be convergent evolution in action. In either case, the coupling of this running surface with the wave-piercing bow is an interesting combination of hull features, and one that would suggest relatively good sea-keeping for a boat of this weight—not to mention excellent surfing capability. The deep skeg, coupled with a large and efficient rudder, should be enough to counteract any tendency to bow steer. Without active stabilizers, she’ll have to rely on the damping effect of the skeg and chines to keep her from rolling.

She does, however, have a rather large waterplane, and the centre of flotation appears to be somewhat aft of the centre of buoyancy. Her prismatic and waterplane coefficients appear to be considerably larger in the aft body than in the fore body. All of this suggests a boat that likes to keep moving, rather than riding out messy weather, and will prefer to take seas on the bow when the weather’s too nasty to keep running at a good clip. When outrunning a following sea, she should be fine, but I suspect that when waves are overtaking her from astern, the seas will tend to lift the stern and stuff the bow. It looks like she has enough reserve buoyancy up front to handle this, but it’d make for a wet ride, and she’ll need a big rudder and strong autopilot to avoid any tendency to broach or bow steer if there’s a real nasty storm coming up from astern.

Part of the advantage of a long, slender hull is that the boat has enough speed potential to get out of the way of most bad weather. Twenty-four hours’ advance notice is enough time for this boat to knock off two hundred miles in pretty much any direction; she won’t outrun a hurricane, but she can most likely dodge one.

Artnautica LRC58 01_small

As for aesthetics, to each his own. The Steve Dashew influence is obvious. I do like this style and think it’s a lot classier than the melted jelly beans (or, in the latest Italian designs, sharp-edged jelly beans) that fill the marina in front of City Hall.

Comparing Costs

Now for the economic problem that plagues long boats: You have to pay to dock them.

Let’s keep our LRC58 in the relatively luxurious Confederation Basin, across the park from City Hall here in Kingston. This year’s seasonal slip rates are $216 a metre, so we’re paying $3850 a year to moor our motor yacht. If we chose, instead, to buy an 11 metre trawler with the same displacement and the same usable living volume, we’d be paying $2375 a year.

So the LRC58 costs an extra $1475 a year in dockage (luxury dockage, in the heart of downtown) compared to her short, fat counterpart. That’s a fair bit to me, but it’s peanuts in the context of half-million dollar boats.

More importantly, though, it’s only about 1000 nautical miles worth of the difference in fuel costs between the LRC58 and the 11 metre trawler with the same livable volume at the same cruise speed. (Our example trawler, which shall remain nameless, burns about 14 litres per hour at 7 knots.)

The extra docking costs of the LRC58 are nullified by the fuel savings if I were to do only four runs a year from Kingston to Toronto or Niagara, a leisurely passage of about 250 miles round trip. If I were to take her out the St. Lawrence to the Maritimes, paying for dockage by the foot along the way, the Artnautica would be financially ahead of the trawler before we reached John’s home base in Nova Scotia.

When we factor in a bit of repair work on the LRC58′s small, simple and easily accessible diesel, relative to the same maintenance on the conventional trawler’s larger and more complex motor, the cost picture is again skewed in favour of Harjamaa’s design.

If, like most powerboat owners, you travel only a few hundred miles in a year and pay through the nose for slip rent, the case in favour of the Artnautica just doesn’t add up. On the other hand, if you’re serious about long-term coastal cruising under power and want the ability to do an ocean crossing if necessary, Harjamaa’s design is likely to be faster, more comfortable, and cheaper to own than we have come to expect from 12-tonne motoryachts.

Membership

Please become a member. Not only will you be supporting in-depth technical series like this one, which are amazingly time consuming to write, you will also get access to our library of 24 online books (and growing) for just $9.99 for the first year.

Comments

So, what do you think of the Artnautica 58. Please leave a comment.

{ 42 comments… add one }

  • Bob N October 6, 2013, 9:59 am

    I’m aware that the helm station is well positioned in relation to the pitching centre but its low height means that vision directly over the bow will be poor. I like it being low because the roll arc at head height will be minimised but I’d opt for giving it a little more height and slightly more distance from the pitch centre to get better forward vision.

    Reply
    • John October 7, 2013, 8:54 am

      Hi Bob,

      I’m not sure that the “vision directly over the bow will be poor”. Dennis gave Phyllis and I a Skype video tour of the boat and the visibility from the inside helm station looked pretty good to us. These things are deceptive. I was on a motorboat the other day where I could have sworn looking at the drawings of said boat that the visibility from the helm would be poor, and it was in real life very good.

      Also there is a raised outside helm station just aft of the wheelhouse on the Artnautica. I’m going to guess that the visibility from both her stations would be significantly better than that from the average aft cockpit sailboat helm.

      Reply
    • Dennis Harjamaa October 7, 2013, 4:29 pm

      Hello Bob,
      The boat has a fairly high bow and looking at the profile is would appear to impede vision a fair bit. I just posted a picture taken from eye height at the helm station on the Facebook page. You will notice that since the bow is fine the visibility is actually better than one would think. I also posted a picture from the exterior steering station.

      Reply
  • james October 6, 2013, 10:21 am

    Here in Europe the cost of berthing this very fine vessel would be prohibitive that is if one could even find a berth.

    Reply
  • Roger October 6, 2013, 12:30 pm

    Great looking design. Put a short, freestanding carbon spar on her and you’d cut the fuel burn in half when motorsailing off the wind.

    Reply
    • Marc Dacey October 6, 2013, 6:34 pm

      I think that has merit, the short mast idea, as would a free-flying Parasailor chute off the bow for downwind “sail assist”. A short mast would also dampen roll in a quartering sea, something to consider in a narrow boat like this.

      This comment, however, gave me pause: “In other words, fully 25% of the boat is fuel – an unusually large figure that implies a serious long-range cruiser.” It also implies (to me) a serious issue with stability numbers as said fuel, which by definition comprises part of the ballast, is used up. If you are down to your last 100 gallons, isn’t the actual waterline going to change along with handling characteristics? Or am I missing something?

      She’s a beauty, regardless. I get the sense I’m looking at the future of distance powerboats instead of the prevalent “trawler/Nordhavn” model (not that I don’t like them as well).

      Reply
      • Matt October 7, 2013, 8:31 am

        You’re not missing anything, Marc. High-fuel-fraction boats often do get a bit twitchy when the tanks run low.
        I’m not sure how much seawater ballast the Artnautica 58 is capable of carrying. She does have freshwater tanks that are good for up to 2.3 tonnes; if a watermaker’s fitted, perhaps they could be topped off en route to partially compensate for lost weight due to fuel burn.

        Reply
        • Marc Dacey October 7, 2013, 2:12 pm

          I suppose the alternative might been ballast tanks that could be selectively filled and later blown with seawater to maintain trim…but that affects power requirements (for pumps and automatic valves), weight and fuel burn, and of course, interior volume.

          I just recall one of the few times I’ve been in a “light load” powerboat in any sort (3-4 feet) of a running sea…it got pretty brutal and not just on the flybridge.

          Reply
        • Dennis Harjamaa October 7, 2013, 4:55 pm

          Gidday Matt,
          First, good job on writing this post.
          I made a bit of a design change a while ago. My original plan was to have two 500 litre water tanks in the engine room but when the quote came in for fabricating said tanks I decided to purchase a simple water maker in stead. The extra cost was not much and the space saving benefits even greater.
          The unit is an Open Ocean made right here in NZ.
          So now I have the option to keep the built-in 1300 litre tank topped up at all times while on passage. This tank is as low in the boat as possible under the lower accommodation sole.

          Reply
      • John October 7, 2013, 8:35 am

        Hi Marc,

        Actually, I don’t think that using up the fuel would have much, if any effect on stability. The reason is that the fuel is in vertical saddle tanks and so when full I’m going to guess that much of the fuel is above the center of gravity. In fact the boat might even get more stable as fuel is used.

        As to the waterline, with the plum bow and stern immersion is going to make very little difference to length, I would think.

        Matt, Dennis?

        Anyway, I gather from Dennis that the boat has great stability and recovery from capsize numbers–way better than most any trawler.

        Reply
        • Marc Dacey October 7, 2013, 2:15 pm

          OK, John…I am familiar with saddle tanks. My buddy in a steel Goderich 40 ketch has them. He uses a cross-transfer pump to improve trim when he’s around half-tank level. I plan to do the same with my water tankage (my fuel tanks are all keel situated).

          Thanks for the explanation.

          Reply
        • Dennis Harjamaa October 7, 2013, 4:42 pm

          The self righting capacity of the boat is unaffected by the fuel load. If anything, she will right herself more readily at lighter loads.
          No doubt she will feel more lively when the fuel load gets lighter. How much that will affect levels of comfort onboard is one of the more interesting questions I’m looking to answer when I get the boat in the water. I have not planned seawater ballast tanks but these could be incorporated in the design if deemed desirable – at a cost to interior volume of course.

          Reply
          • Marc Dacey October 7, 2013, 8:49 pm

            Thanks, Dennis, and may I say it’s a privilege to have the fellow who drew and is building Hull No. 1 to go deeper into the design elements.

            One thing I *think* I see from the 3D drawing are cambered decks…is this the case?

          • Dennis Harjamaa October 7, 2013, 9:01 pm

            Hello Marc,
            Yes, the fore deck is cambered apart from an 800mm flat strip along the centreline. I did this to make hatch and ventilator installations easier.
            The pilothouse roof is in three flat sections and the cockpit sole is flat but with one degree fall aft.

    • John October 7, 2013, 8:46 am

      Hi Roger,

      Actually, in my experiences, and I have motor sailed a lot offshore, motor sailing does not work off the wind because the apparent wind is so low, particularly in the lulls, that the sail starts crashing about. It also has very little fuel burn benefit when off the wind for the same reason. A sailboat may wish to tack down wind in this case, but that would not make sense for this boat because the increased distance would outweigh any fuel burn savings from filling the sail.

      Motor sailing does work well reaching but of course not dead up wind. So we have to ask ourselves whether or not the additional cost and complications of a rig and the design changes required–you can’t just stick a rig in the boat as is, it will have effects on the whole design–would be worth it. I don’t know, but I’m going to guess not. Matt, Dennis?

      Reply
    • Dennis Harjamaa October 7, 2013, 5:09 pm

      Hello Roger,
      I’m planning an emergency backup sail rig to help me drift controllable towards land in case the engine gives up.
      The plan is to use one of the two booms as a mast, hoisting it up and securing it up with a forestry and shrouds to the aft corners of the cockpit.
      This is not fully detailed up yet, it’s a bit of a tricky one since I want the whole shebang to be able to fold down for getting access into the European canals.
      An alternative could well be a kite by Omega Sails in France. If anyone has first hand experience with one of these I would be very keen to hear. The French Ecotroll uses one.

      Reply
  • pat synge October 6, 2013, 7:04 pm

    A minor point but why the forward raked front to the deckhouse? Surely the wind resistance is significant. A sleeker profile would provide more space below while reducing wind resistance. Perhaps not significant in calm conditions but when pushing into 40 knots it would be noticeable.

    Reply
    • John October 7, 2013, 8:30 am

      Hi Pat,

      As part of my project of learning a bit more about power boats I have spoken to several experienced owners, including one circumnavigator. They have told me that reverse raked windows are highly desirable and much better than the those where the bottom of the window is forward of the top for three reasons:

      • Improves visibility by reducing reflections from gear in the wheelhouse.
      • Sheds water better
      • Is much cooler in hot climates

      I guess those reasons outweigh any slight drag advantage.

      This is probably why most commercial vessels that I’m seeing today have reverse slanting windows like this boat.

      Reply
    • Matt October 7, 2013, 8:37 am

      The air resistance on a 4 square metre (frontal area) deckhouse with vertical or forward-raked windows in 40 knots apparent wind is just a hair over 1.0 kN. That takes about 4.2 hp to overcome, if the boat’s doing six knots. Streamlining the wheelhouse like a car windshield would save up to 2 hp of that, but you’d lose wheelhouse space and get a lot more glare on the windows. I think the improved visibility is a fair tradeoff for burning an extra cup or two of fuel per hour on those rare times when you have a 40 kt headwind.

      Reply
      • Dennis Harjamaa October 7, 2013, 5:22 pm

        All the necessary comments have already been made in favour of the forward slanting windows except my favourite one: they look the business!

        Reply
        • John October 7, 2013, 6:28 pm

          Hi Dennis,

          I secretly really wanted to say that!

          Reply
  • Eric Klem October 7, 2013, 1:28 pm

    Hi Matt,

    Thank you for the analysis. I was wondering whether you could comment on how you think that this boat will do going right into bad weather as you have mentioned that this will necessarily be an important storm tactic. I guess that my question is really about how much energy is dissipated by the motion of the hull and the wave action against it at different speeds as opposed to how much power is available. In my own boat which pitches a lot more than I would like in these conditions, we need a lot of power to maintain a very slow speed (and sometimes we don’t have enough and can’t keep the bow into it using the engine). A few years ago, I was sailing up the New England coast and passed Wind Horse as it was headed south into quite choppy ~8′ waves. While the conditions were certainly not very bad, I was impressed by how level the boat stayed and how little horsepower it appeared to take to move along at a nice pace.

    I have no experience on this type of hull form but I have been on a number of boats with much higher power to displacement ratios and reasonably quick lines that are unable to stay head to wind in conditions that I would not consider very bad. What I am really getting at is how do you think this boat would do in really rough conditions? If the main storm tactic is to slowly jog into it, is 75 hp enough for the hull design to keep the bow into 30′+ breaking waves and 50 knots of breeze should you get trapped and be unable to outrun the storm?

    I am not particularly familiar with this specific design but a vessel that relies on a single form of propulsion does scare me a bit. Maybe I missed a get-home option but it seems like you would need this and a backup option for heavy weather as well. In general, I think that it is a really appealing design and maybe I am just being too conservative.

    Eric

    Reply
    • John October 7, 2013, 2:15 pm

      Hi Eric,

      On the issue of backup power. I discussed that with Dennis. For his own boat he is planning to experiment with the new French kite sails that are designed for that purpose.

      He also stated that there is plenty of room on the port side to fit a small get-home engine. Having said that, and talked at length with several motorboat owners, I think that get-home engines are often an illusionary security, particularly in the situation you postulate, since they don’t have enough power to be useful.

      I think that if I were to buy an Artnautica I would first need to satisfy myself that she could safely lie to a Jordan Series Drogue off the stern in storm force conditions without power. My guess, and it is just that, is that she would do fine in that configuration since the JSD would prevent her from accelerating down a wave face to a speed where any tendency to bow stuff or steer would become a problem.

      Having said all that. I’m just as interested as you in her ability to jog upwind into storm conditions. Here I think that she might surprise us to the positive side because the rig in sailboats, as you would know, has a huge effect on pitching moment–no rig, much less pitching.

      The was graphically demonstrated to a friend of mine two falls ago when motoring into a nasty swell trying to get out of Buzzards Bay in a 60-foot ketch equipped with 150 hp engine and a big fixed prop. Another friend in a Nordhavn 46 came past them like they were standing still, despite being a much smaller boat with less horsepower. Of course there are a lot of variables, but as far as the two friends could see, the big difference was that the motor boat was just pitching less.

      We have also noted the same thing in our own boat: since we replaced our old cracked aluminium mast with a carbon mast, our speed under motor upwind into waves is much improved even with no sail up and we just don’t get stopped by pitching, even though we only have 87 Hp in a boat that is much heavier than the Artnautica.

      Reply
      • Erik de Jong October 7, 2013, 3:02 pm

        On the topic of “getting home”; the majority of the cargo ships that log around 1.5 to 2 million NM during their economical lives, do with just a single engine as well. They just have to fix it to such a level that it can bring them to port. In the old days, major main engine repairs had to be done on a monthly basis or even more frequent, in the modern days this barely ever happens.

        I don’t think that there is a big probability that one will encounter an engine failure that can’t be (temporarily) repaired at sea if the proper tools and spare parts are carried. Assuming that the level of maintenance of the engine and attached systems is raised to an art.

        Reply
        • John October 7, 2013, 3:56 pm

          Hi Erik,

          I would agree with that. In some 45 years of going offshore with diesel engines I have only had two failures and in each case we were able to fix them at sea.

          The secret seems to be good maintenance, some parts and tools, and a bit of basic common sense.

          My friend Bob T, a professional mariner, fleet fisherman, and sailboat owner tells me that in his some 50 years (he started young fishing with his uncle) he has never had a diesel engine fail to bring him home. Bob has just bought a single engine powerboat and actively rejected twin engine versions of the same model.

          Reply
          • Eric Klem October 7, 2013, 9:37 pm

            Erik and John,

            While I agree with both of you that a single diesel engine is actually remarkably reliable, I fear that this would not work for a large portion of the cruising community due to a lack of comfort with making repairs at sea. Maybe the answer would be that the cruising community needs to become better educated about repairing these engines and their systems as well as caring appropriate tools and spares. Realistically, rebuilding an engine is really not any harder than setting up a jury rig if your mast just went over the side if you have ever done one before (I might be a bit biased here as I used to design industrial air compressors which are basically diesel engines minus the fuel system). On my own boat, the most difficult part is that I would have to take the engine out to pull any major components as I can’t get the head or pan off due to height constraints in the engine compartment.

            Something else to think about is that many twin engine setups are not really independent and give a false sense of security.

            Eric

      • Eric Klem October 7, 2013, 9:13 pm

        Hi John,

        Thank you for the reply. I think that all of the points that you make are good.

        You make a very good point about the relationship between the polar moment of inertia about the pitch axis and the ability to motor to weather. Yet another reason to keep the weight in the rig and the ends of the boat to a minimum. I couldn’t see in the pictures of the design whether the anchor chain is stored back from the bow but that would probably help a lot.

        As you suggest, the combination of a JSD and some form of sail as the get home option seems like the best route to go to me. I wonder what Dennis’ actual plan for heavy weather is and whether it is the JSD?

        Eric

        Reply
        • Dennis Harjamaa October 8, 2013, 2:12 am

          I have read a lot of good things about a Jordan Series Drogue and one of those will likely be part of the inventory.

          Reply
          • John October 8, 2013, 9:03 am

            Hi Dennis,

            You might want to consider incorporating the strong points required for the JSD now, while you are building. Also, I would think about adding built in storage so that it can remain ready to deploy at all times. We detail all of that, together with chapters on deployment and retrieval in our Heavy Weather Online Book.

          • Dennis Harjamaa October 8, 2013, 4:38 pm

            Hi John,
            I’ve had in mind that the bollards in the cockpit would work well with a JSD. I’ll read the book to confirm what else I can incorporate into the boat to make handling the gear easier.

    • Matt October 7, 2013, 2:46 pm

      Re. staying head to wind in bad weather.
      Without a model test in a wave tank, it’s hard to say for sure. My suspicion, backed by no calculations at all and based only on what others have reported about boats with similar proportions and similarly fine wave-piercing bows, is that:
      Force 7, she’ll be able to make headway dead upwind.
      Force 8, VMG to windward will be only a couple of knots but she’ll be able to hold a more-or-less steady course.
      Force 9, probably close to the limit for beating into a head sea, might be able to keep head to wind but won’t be making any headway.
      Force 10, you’d better have the JSD out by now.

      To elaborate a bit more. The added resistance a hull experiences in a head sea is strongly dependent on:
      - Its tendency to pitch (a relatively low pitch moment of inertia, i.e. weight concentrated near the centre, is preferred).
      - The shape presented by the forebody and bow topsides when cutting through a wave (a narrow, streamlined bow can part a big wave with relatively little resistance; the resistance goes up dramatically when you get a wider, fuller bow that tens to bash into the wave, throwing breakers to both sides). Or, in other terms, how big a change in momentum do you have to impart to the water to move it out of your way.
      The Artnautica 58 would appear to fall considerably on the favourable side of average in both of these characteristics.

      Re. get-home power.
      This is a topic worthy of several articles on its own. My general opinion of low-powered “wing” engines is pretty poor. Many failures that would cripple a main engine (a net wrapped around the prop, running aground, wet cruddy fuel, a lightning strike blowing out the ECU, an engine room fire, etc.) will take out the wing engine at the same time. And, in a storm situation, an off-centre engine sized for limping home at 5 knots may be of little help. I do like the kite idea, and the Dashew approach of jury-rigging a staysail from the dinghy cranes, as “if all else fails” contingency plans.

      Reply
      • Eric Klem October 7, 2013, 9:26 pm

        Matt,

        Thanks for ballpark guesses, they seem quite reasonable and confirm my suspicion that the ultimate heavy weather tactic cannot be reliant on the engine alone because it would require more power.

        I have always thought that the design of boats is funny in that it often results in an unstable set of forces when pushed past normal limits. The fact that the thrust is back aft and the resistive forces are mostly up forward when pushing into weather mean that the boat wants to spin around. And then at anchor, a lot of boats have a lot of windage forward and a CLR quite far aft (not talking about the Artnautica here) so they are again unstable. I wonder whether someone will eventually be able to come up with a way to overcome these issues without introducing even worse ones or badly compromising everyday efficiency. Overcoming the instability of the location of the thrust could go a long way towards making a boat that can hold its own motoring into heavy weather without a lot of power, just look at how many boats with narrow sterns actually back to weather better than they go forwards because they are not putting a ton of energy into steering.

        Eric

        Reply
  • Dick Stevenson October 7, 2013, 4:05 pm

    Pat and all,
    I believe those forward raked windows with such a salty feel are called Portuguese windows/configuration and are designed to allow better visibility. Conventional windshields reflect all the instrument lights right back into the helmsperson’s eyes, unless the “dashboard” is very well thought through (eg kept dark- like an automobiles). and that is all one sees, the reflected instruments. Reverse raking pulls the reflection off the ceiling which should be dark, and then one is able to see forward through the window much better.
    Dick Stevenson, s/v Alchemy

    Reply
  • Dick Stevenson October 8, 2013, 11:54 am

    While we are all having fun designing Dennis’s boat, I would give a lot of credit to a designer who incorporated a reservoir for good oil waiting to be used, a reservoir for storing one change of old oil plus a tranny oil change and while we are at it, a built in gasoline tank for dinghy engine fuel. Those elements would go a long way to convince me that the designer had cruisers in mind.
    Dick Stevenson, s/v Alchemy

    Reply
    • Matt Marsh October 8, 2013, 1:00 pm

      Good ideas about the service fluid tanks, Dick. (Although I would personally prefer a dedicated locker with secure slots for several jerry cans of dinghy gas rather than a built-in tank). I have lost count of how many plastic pop bottles full of waste oil are lying around my place, waiting for the day when the hazmat depot is open at a reasonable hour.

      Reply
    • Dennis Harjamaa October 8, 2013, 4:49 pm

      Hello Dick,
      Very good point. My plan is to finalise the system installations in the engine room and see what sort of space I have left over. So far it looks like I can weld up a couple of tanks to fit between the stringers for clean and dirty oil. These will bolt on so can be removed for filling and emptying.
      I have a locker on deck for two propane bottles and a couple of jugs of petrol.

      Reply
  • Dick Stevenson October 8, 2013, 5:36 pm

    Dennis, There are some things that in home waters one does not deem important. Then when you try to store a few oil changes and worry that the plastic containers will break etc etc. Someone will bless you in the future for your thoughtfulness. Good luck, Dick

    Reply
    • John October 8, 2013, 5:57 pm

      Here, here!

      Reply
      • Dennis Harjamaa October 9, 2013, 7:19 pm

        I would like to take this opportunity to thank John, Matt and the rest of the team for showcasing my boat and all the readers who made comments. It has been exciting and educational. Thank you!

        Reply
        • Marc Dacey October 10, 2013, 12:44 am

          Dennis, we may never meet in real life, but I’m sure that we share with a lot of the sailors here the feeling of being the only guy in the world trying to transform an idea into reality.

          It’s the story of every person who’s bought a boat intending to go out of sight of land. I’m sure a lot of the comments here, of use to you or not, were offered up in that spirit.

          Reply
        • John October 10, 2013, 7:57 am

          Hi Dennis,

          You’re welcome. You deserve all the help we can render for going out on limb and actually building a boat that is not just another too short trawler with too much interior. We can’t wait to see your boat in the water.

          Reply
        • Eric Klem October 10, 2013, 8:43 am

          Dennis,

          Thank you for participating in this thread, it is really amazing to have the designer of a very cool boat take the time to participate and do so in such a constructive and open way.

          Eric

          Reply

Leave a Comment

Please read our Comment Guidelines before you comment.
If your comment does not display immediately, please contact us
.
Your e-mail address will not be displayed and we will not send you junk mail.


Get your own avatar like ours.
Avatars

Previous Post (by date):

Next Post (by date):