Offshore Motorboats and an Ideal Geezer Boat


Phyllis and I often talk about what our ideal old age boat would be…Oh, Ok, older age…you lot are some rude.

Be that as it may, I recently came across the Seapiper 35, which comes pretty close to fitting the bill.

Given the huge cockpit forward of the wheelhouse, I wouldn’t take the boat far offshore, but she would make a really nice coastal cruiser, and the price at US$150,000, well tricked out, is certainly compelling.

The Seapiper 35 would be a fun boat to poke around the bays of Nova Scotia, and I guess I would even take her to Newfoundland, although I would be right-careful about the weather on the crossing of Cabot Strait.

Anyway, it’s great to see a company coming up with an innovative design based on an efficient hull form.

Ritzo Muntinga, the guy behind the Seapiper, tells me that they already have four boats on order, so it sounds like the concept is working.

He also explained the logic behind the centre cockpit:


Over the past couple of years I have also been penciling various alternative layouts with an aft cockpit within 8ft-6in beam. The main drawback of an aft cockpit is that you end up with a narrow pilothouse interior width, at least for part of it (you need side decks to have reasonable access to the foredeck).

Overall an aft cockpit in our size range brings with it design compromises that I find less appealing so at this point I am not planning on a SeaPiper version with an alternative floor plan. The 8ft-6in overall beam and the current center cockpit are important pieces of the puzzle that make it work. …And remember that the cockpit can easily be covered with a bimini type sunshade which will also keep you out of the rain.

…There are eight 2″ x 6″ side scuppers on each side of the cockpit for a total of 16 with an area of about 180 sq in. In a worst case scenario: the large center cockpit filled to the rail will drain in about 15 seconds. The floor hatches in the cockpit sole have 1-1/4 inch high coamings with neoprene seals and they make use of the same overboard drain system.

Although a 15-second drain time on a cockpit this big in relation to the boat size is too much to be safe offshore—a new wave can refill before the old one drains—Ritzo’s thoughts make sense to me. When designing a boat you need to figure out what you are trying to do and then stick with that and not try to be all things to all people, a mistake that will inevitably lead to a compromise boat that’s not good at anything.

The other thing that jumped out at me in my quick look through the web site was that, even though the price is low, Seapiper seems to be putting good gear on the boat, not just cramming on a lot of the cheapest junk they can find to tick a box. Shows that an inexpensive boat does not need to be a junk boat, as long as you focus on what really matters.

Anyway, Phyllis and I still want to be able to go offshore and still like the sailing thing, so the Seapiper is not a boat for us yet, but who knows what Ritzo, who is clearly an innovative guy, might do in the future. Maybe come up with an offshore boat. We will be watching.


Artnautica LRC58 02

Talking of motorboats, over the last year I have been working off and on with Dennis at Artnautica Yacht Design, on a modified version of the LRC 58 that we are calling the Adventure version. Not sure when it will see the light of day (we are both busy as hell) but it is a fun project that will, I think, yield a version of the boat for those wanting to push things a bit, like, for example, heading for the high latitudes.

Black Swan Yachts

I also had a long and interesting Skype chat with Todd Rickard, who used to be with Steve Dashew and is now off on his own at Kooldjak Marine, about his plans to specialize in efficient safe offshore motorboats. He’s partnering with Nigel Irens, one of the most innovative designers in the business.

Finally, Sensible Motorboats

The bottom line in all of this is that we are finally seeing a trend toward innovative and efficient motorboats and away from fat trawlers with condo interiors.

Latest Dashew

Talking of Steve Dashew (the father of this recent trend toward efficient offshore powerboats), I have been following the evolution of his latest personal boat over at Setsail. All I can say is, “what a machine”. I gather from Steve that they are not far from launching.

The boat itself is only of academic interest, unless you are seriously wealthy, but there is still a lot to learn for all of us from watching a couple as deeply experienced as Steve and Linda build their ultimate boat…for about the fifth time.

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Hi John,

I was checking Seapiper 35 some time ago and reached the same conclusion as you; looks like a great coastal boat at a good price.

Regarding notable motorboats with the adventure/expedition attribute but without the attainable/affordable one; what are your thoughts on Watson 72 expedition motor boat (
These guys seem to produce exceptionally well made ‘little ships’ in New Zealand but they seem to do it under the radar.



As you said each on its own but I think they deserve to be mentioned as serious adventure/expedition machines.
I have done extensive research in displacement motorboats (they are the only other thing that interests me apart from quality sailboats) and some passages in FRP production trawler yachts (most of my miles are on sailboats) and in my opinion when it comes to saying there is a lot of boat for a certain waterline it depends how the boat’s volume is distributed on this short waterline length. The W48 is the only production trawler yacht I have found with high volume distribution below the waterline i.e. it has deep draft ( turns a 40 in wheel !), fine entry and a somewhat narrow beam for its length
So yes it is heavy but it should not be necessarily inefficient or not economical to run in comparison with Morgan’s cloud.



You can’t break the laws of hydrodynamics. You can’t even bend them. They are very unforgiving.

Once you’ve set the design displacement and the cruise speed, the most efficient values for all the other parameters – length, beam, prismatic coefficients, etc. – are basically set. On some of them, you can compromise a bit (eg. less length and more beam, as many trawler builders do) at the cost of efficiency. On others, you can’t compromise at all (eg. if your prismatic coefficients, which describe the distribution of underwater volume, are off by 5% from ideal, the boat will be severely compromised).

Most designers know this, at least on an academic level. Many of them don’t really understand it, and are too easily swayed by marketing types who don’t know hydrodynamics at all.

If you want efficiency, look for a motorboat whose proportions and figures indiciate that it’s actually designed for efficiency.

Jim R

Any kind of time frame on the “Adventure LRC 58”? Availability in North America?


Hi John,
Like you always advocate boats are a compromise. So if I have to put a limit on the LOA of an ocean crossing capable displacement motor boat, say just below 15 m for affordability reasons then the Displacement Length Ratio (D/L) has to be high as to be able to carry enough fuel and supplies. What I prefer (among other design features) is to have this done by going down (deeper draft with a nice deep V fore and a deeper wine bottle shape aft or something approximating that) and keeping the waterline beam relatively narrow rather than going with wide beam and shallow draft as it is the current trend in production trawler yachts.
Although not really comparable, a sailboat with the same length might seem more efficient under power but I think this is probably not the whole picture because as you already stated there are large mechanical propulsion inefficiencies and also specific design aspects etc. Moreover I do not think you can make an ocean crossing motorboat out of a similar length sailboat hull.
What I would like to know more about are the economics of cruising with a 15 m sailboat vs a 15 m power boat, from purchase to running expenses. Though not entirely sure I think a quality 15 m sailboat should cost around the same as a similar quality 15 m displacement yacht but from there on I do not seem to be able to quantify the differences.
Any thoughts on a future article on that?


Alan S

Hi John, just for interest Passagemaker is alive and well. She was rescued by the current owner in 2008 and since then has been cruising around the Carribbean. He has even increased the main mast height. See


Hi John,

Marina fees are exactly the issue here when it comes down to having an ‘attainable’/affordable dispacement power boat able to cross oceans and that limits the choices of many ordinary people. Robert Beebee’s Passagemaker displaces 27 tons (out of those 5 000 lbs are ballast) on a 50’ 0″ LOA and 46’6″ LWL, beam 15’0″ and that is no lightweight or especially narrow either.
So even though I do understand and do partially agree with the benefits of your suggested motorboat designs I do not see those as being attainable (by me at least and for my reality and intended cruising)



“I would highly recommend getting a copy of Voyaging Under Power, where all of this is very well explained.”


Which edition would you get?

They say the older ones are better?


Hi John,

I have both Leishman and Umstot editions. Could not find Pc for Passagemaker.
There is a nice table (from D. phililips-Brit’s Naval Architecture of Small Craft) in Leishman edition showing the correct Pc for various S/L values. Starting from specifying a certain LOA, consulting that table and considering numerous other things (that would make a very long post) I reached my conclusions (and necessary compromises) that describe what would theoriticaly suit me.

In doing, so among other sources, I consulted the ‘Attainable adventure cruising’ site many times as it represents one of the most reliable, valuable, objective, etc online (and offline) cruising resource.

Thanks for that




I’ve purchased the Umstot edition.

The chapter on roll stabilization is very interesting. Having only sea experience in sailing yachts, it didn’t realize it was such a concern with power boats. Have you written this topic up at all?




Regarding roll stabilization, I made some (hare brained?) suggestions on the LRC58 design page to Dennis hoping he might comment. Neither he nor any body else made any comments so I presume they were too far out in left field.

“Firstly, for roll frequency control (and also pitch control for that matter), I am thinking of a shortish vertical mast section (could be the aerial, radar mast), of appropriate diameter, and pump filled with water when fast rolling/pitching was a problem. Being up high, not so much water would be required and of course space robbing ballast tanks would not be needed. Although it may require dimensions (but I suspect it won’t) such that it looks like a ship’s funnel and ruin the aesthetic. I’d be interested to know if anybody’s done this somewhere and how it performed.

Modern roll stabilization is effected by bilge hung foils. Obviously, these are a collision/grounding risk and increase hydrodynamic resistance. They can also have an impact on the vessel’s steering, being off the centre line.

My idea is to hang a single foil behind a keel placed at or near the vessel’s turning centre (so there is minimal impact on steerage). If the keel is already designed in then there would be little additional hydrodynamic resistance and no additional collision/grounding risk. I posted the idea into Steve Dashew’s blog. He seemed to think it might have merit.

Now modern stabilizer fins are driven by hydraulic rams, I believe, and controlled by sophisticated sensors and electronics. My idea here is to take the keel hung foil and from the foil’s shaft suspend a mass which can swing in a horizontal (when the vessel is level) plane. When the vessel rolls the mass will swing in such a way to turn the foil so as to generate lift opposing the roll sense. The mass and the radius of the arm it is suspended from would have to be appropriately dimensioned relative to the foil and the speed of the vessel. Arrangements would have to made to prevent the mass swinging violently if a knockdown or inversion occurs. This kind of arrangement might also work for bilge hung foils, if they were more vertical than horizontal, with some thought. No power to be consumed, no fancy electronics or hydraulics to fail. (Just a potentially out of control rogue mass!)

The other idea for roll stabilization is to use high pressure water jets.
There are water jet systems used for bow/stern thrusters e.g.,

The systems as configured are very straightforward. Of course roll stabilization would require sensors and control electronics. The jets could be located at the base of a keel or at the extreme edge of the bilge pointing downwards. I asked Steve D. about this. He said they had used jet bow thrusters in the 80s without success and saw no reason to consider them. I cannot see why they would not function as required if adequately sized. Maybe this is the problem. Too much power might be required. If they could be made to work, then there is minimal collision/grounding risk and minimal additional hydrodynamic resistance.

The same approach could be used for pitch control with stern and bow thrusters although I would imagine even more powerful jets would be necessary.

(By the way, the idea of suspending inertial masses in a vessel stirs the notion of connecting generators to them such that rolling and pitching might be used to harvest the energy of waves impacting a vessel.)”



Did Steve explain why flume tanks would not work on his FPBs?



You should read:

This bulletin is very circumspect about anti-roll tanks.



Thanks for the link. This is a great website with loads of information.

I don’t want you to give you the impression I have a negative view on flume tanks – I really don’t know. However, I think it’s worth looking at every piece of information possible. You might also want to take a look at page 22 of the following report:

It has a pie chart showing the use of roll-damping systems in the Quebec fishing fleet. Paravanes usage is the highest at 51% and flume tanks the lowest at 1%. It might be worth finding some of these 1%ers and see what they have to say.

As for paravanes, while they may be effective, the paraphernalia associated with them I think is considerable. May as well stick with a sailing yacht.

The same chart in this report says that 9% use bilge keels. These sort of appeal to me, however, I would look at a retractable system. Why not? Racing yachts use retractable fins for hull balance and windward lift.

The more you read, the loud and clear message is that the most effective system is a powered moving fin type. If power isn’t an issue, I think a jet system might be worth investigating.

This is much vexed but critical question for powerboating. Look forward to your article.


“Michael Kasten designed a very nice little trawler with flume tank that has made many hard voyages.”


Which design is that?

Jim Trefethen

Hi John
The Seapiper 35 is indeed an intriguing design. I have long been an admirer of George Bueller’s sail-assisted Diesel Duck 38, which is a similar concept but way more expensive to build.

Years ago, I cruised extensively in Eastern Canada and New England in a 40-foot antique powerboat and vowed never to own another stinker that didn’t have adequate stabilization. I suspect that the Seapiper will roll like an ecstasy-afflicted southern preacher in any kind of beam sea, regardless of the narrow beam and low center of gravity.

The best stabilization for a geezer boat (I’m 74 so I am looking at likely candidates) seems to be a simple get-home sail rig, such as on the Diesel Duck. Flopper stoppers of an adequate size to work well are too difficult for elderly folks to deploy and dangerous in the right conditions ( look at what happened to George Clooney in the Perfect Storm), so don’t count in my version of the ideal old-guy live-aboard power cruiser. Gyros, of course, are a technological absurdity on a small boat. The only other essential addition that I can see is lots more ventilation: opening ports and windows and a few dorade boxes would do the job nicely.

I suspect the designer could add a short mast with a derrick-style boom and big foresail for a reasonable price, and the improved ventilation would be a simple matter. Adequate scuppers in the center cockpit could be incorporated under the two deck boxes by lifting them up a few inches. So yeah, great design that is now on my short list. Thanks for posting.

Jim Trefethen

Thanks for the clarification John.

I realize these two boats (Seapiper and diesel Duck) aren’t really comparable: just for the difference in displacement if for no other reason (which also explains the large price disparity). A better comparison might be the Little Island Trader, designed by Karl Stambaugh at Chesapeake Marine Design, which can be built to 34 feet with about the same displacement as Seapiper–realizing that the wider beam and round bilges of the Stambaugh design would make the sail necessary for stability. I investigated an aluminum 30-foot version of this boat that was being built in Canada, but it was too small for our needs, and I was suspicious of the builders motivations in putting it on the market immediately after launch–even before the interior was finished–without an adequate explanation. Not many of these have been built so, as for as I’m concerned, it is still untested.

Anyway, there isn’t anything I don’t like about the Sandpiper, so it is now my new dream boat (correct: I am a bit fickle when it comes to dream boats). Can’t wait to see one.


I saw this post on the Seapiper blog last year about a motorsailer variant.

I haven’t seen anything since but they have been busy. Anyway, if they follow through there is your sail for stabilization and backup power Jim.


“I have been working off and on with Dennis at Artnautica Yacht Design, on a modified version of the LRC 58 that we are calling the Adventure version.”


Do you have any information about the dynamic performance of the LRC58 at sea, particularly now that there is a fully completed and fitted out version?

Last year I asked Dennis when he appeared in here whether he had a stability curve for the boat. Do you know if he has produced one yet?



I am puzzled by the fact that Dennis has never published a stability curve and when I asked about this last year I think he said he hadn’t worked one up. So how can he make the claims that he has?

Dennis claims the boat will self right from an inverted position. This is probably because of the nicely protruding saloon/pilot house. But what worries me is how easily it inverts and once it begins to recover how quickly it will return to an even keel. I suspect that it could hang twixt inversion and being upright too easily given its light displacement and the lack of deeper ballast. I suspect the angle of vanishing stability is closer to 90d than to 130d. I may well be wrong about all this but I can’t see why there isn’t a published stability curve.

I think Dennis has done a fantastic job in designing this vessel (and self building the prototype) . OK, a lot has been borrowed from Dashew, but I think it is a breakthru design, aesthetically and conceptually. However, at the least, the static stability issues have to be clarified. The dynamic stability issues are more difficult to clarify a priori – only experience at sea will tell.


” While there is a superficial resemblance, the hull forms are radically different. ”


Yes, I would agree, even more so compared to Steve’s latest designs.

The LRC58 has almost a semi displacement form, with its low displacement, broad stern and flattish aft underbody.

Carl E.

Hi John,

Do you think it a big disadvantage that the LRC 58’s engine room can only be reached via the open cockpit (and then through the lazarette) underway and in heavier weather? I guess it depends on the value you place on (very) regular engine room checks underway and the degree on which electronic monitoring is available?


Hi John,
Can’t say that the Seapiper 35 is something I dream of finding in my Christmas stocking. And I question how comfortable it will be anchored in a bay where the swell from freighter traffic rolls in every few minutes! Granted it is a flatish bottom chine hull, not the mastless sailboat hull that is my point of reference, but 8.5′ is a narrow boat .

Second, I have to wonder how long a boat building company building this design in California will be able to sell it for $150k. Hasn’t worked for any body else .

On the question of fuel efficiency, if you compare it to a totally different approach to designing a fuel efficient coastal cruiser it doesn’t look so exceptional. For example, consider this tunnel hull catamaran with a unique single engine configuration.
At 7.25 knots it gets 6.9 MPG, but it is capable of running over 20 knots with something like twice the fuel burn. The air cushion in the tunnel softens the ride— I’d expect it to be much more comfortable than the SeaPiper underweigh. At least as much interior volume even though it is a 32 instead of a 35. And it fits into a standard 32′ slip at a marina of your choice.

Not an offshore cruiser, but neither is the SeaPiper.

Different boats for different folks!

Carl E.

Hi John,

At first glance this looks like a sensible design for coastal cruising:

Oddly for a European builder, they don’t mention which CE classification they aimed for. Sales seem to be limited to Europe at the moment.

Carl E.

Hi John,

Not entirely sure this fits all your criteria, but Nordhavn is developing a smaller boat (41 ft.):

CE-A, price around USD 700,000.

They did get the memo’s on maximum waterline length and twin engines :).

Carl E.

Hi John,

Unfortunately not yet. Membership of is free however and is for me spam-free.

I could mail you the image and PDF Nordhavn published there otherwise?

You mentioned previously your aversion to non-production line-boats; in terms of resale Nordhavn is as good as it gets apparently.

Carl E.

Hi John,

The first official pages have appeared on the Nordhavn Europe-site:

Apparently they’re still waiting for some exterior renderings before the Nordhavn mothership will publish.

Carl E.

Hi John,

The indication Dan Streech gave in the Nordhavn Dreamers group was $700,000,- including delivery to Florida. The above mentioned official pages don’t mention price, unfortunately.

One or more substantial houses to be sure, but a very decent spec in addition to the Nordhavn name and presumably, robustness.

Kit Laughlin

John, thanks sincerely for all this. I am commenting only to get all comments on this article, and especially when you update the “I have been working off and on with Dennis at Artnautica Yacht Design, on a modified version of the LRC 58 that we are calling the Adventure version”. Bliss.
Steve’s yachts will always be out of my price range (and for me they are too complex and too refined, fitout-wise), but am looking forward to an Adventure power boat version from one of the other builders. And in the meantime, am using my 40′ wooden ex-cray boat to travel and understand marine systems (and how to reliably dock a single engine boat with no thrusters).
Thanks again; I am pleased to be a subscriber.

Kit Laughlin

I agree: the SeaPiper will not be that boat. Some of Michael Kasten’s designs look excellent, but his focus is design—and the end result re. seaworthiness and ultimate safety is all in the details of how these designs are built and fitted.

Lee Corwin

Own an Outbound 46. Perhaps the best current boat still in construction for mom and pop open ocean cruising. Know her warts and pimples well. If you’re interested contact me to discuss . If you go to the Outbound owners group you can see these issues are fairly common. Still compared to friends cruising other boats in this class the Outbound is a jewel.
Please realize every Outbound is different. As boat has evolved over the years Phil has incorporated the good ideas from successive owners to modify base boat but there’s a large diversity of opinion has how to rig, do interior, spec, and outfit.
Looking to transition to a DD in a few years. Contacted China.Received stability information which I cannot translate into anything I understand. Use to Gz curves and AVS. An article on the numbers used by the trawler crowd to describe a vessel would be most helpful.

Özgür Demirtaş

Hi John,

What would be your opinion about the Korvet 18 Long Range from Deep Water Yachts?