Trade Offs in Yacht Design

Arrangement plan, kindness of Ian McCurdy, McCurdy and Rhodes Naval Architects. Click on Plan to see larger.
Arrangement plan, kindness of Ian McCurdy, McCurdy and Rhodes Naval Architects. Click on Plan to see larger.

Eric Klem, engineer, frequent and erudite commenter, and sailor, came up with some great thoughts on my Adventure 40 interior post. I started to address each of his concerns in the comments, but then it struck me that we had the basis of a good discussion on the inevitable compromises that must be made in designing or living aboard any voyaging boat. (Also, thanks to Richard (RDE) Elder for his comments to the same post that influenced several of my thoughts below.)

Please understand that this post is really not about the specific details that Eric and I discuss, but rather demonstrates that you simply can’t have it all, and that every decision you make will have side effects, some of them undesirable. Whether or not you end up with a good boat is about how you handle those compromises.

So imagine, if you will, Eric and I sitting in the pub over a couple of beers.

Engine Access:

Eric: One question I have is about engine placement. I assume that you have the engine in the traditional place under the companionway steps instead of doing something like the Passport 40 [further forward under the galley].

If this is the case, the interior arrangement will have a huge effect on how easy the engine is to work on. I like the general arrangement that you outlined but I am a little concerned that putting the shower and head where the chart table is on Selkie might make it very difficult to get access to the starboard side of the engine.

Unfortunately, it seems like the only things that provide decent access while doing double duty are berths and stowage. Since the port side is already compromised by the galley, maybe making the engine room wider than necessary so that someone can crawl along the side of it would be a reasonable compromise.

John: Eric, that’s a very good point, good engine access is vital. If necessary I would sacrifice galley and shower space to preserve it, as you say. However I really don’t like the idea of crawling in next to the engine.

How about this? We make the shower stall, in effect, an extension of the equipment bay—more of a passage closed by curtains, with a drain in the floor, rather than an enclosed stall? Then what we can do is put a big hatch in the inboard side of the shower (gasketed of course) that will give good access to the engine.

That coupled with steps that are hinged at the top and lift up will give great access to the front and starboard side of the engine and all the way back to the drive train and rudder post. Of course, we will need to make sure that we don’t crowd the port side of the engine too closely with the galley, just as you say and we must be willing to sacrifice galley space to do that.

Eric: Eliminating the nav station would eliminate room for the electrical panel. I like this to be close to the companionway so that I can easily pop down and switch on the nav lights or something like that but I also think that it needs to be far enough from the companionway that it doesn’t get soaked all the time.

John:  Hum, I hear you, but let’s look at the trade offs. If we site the panel in the equipment bay we will reap big time cost and simplicity benefits by having it close to the batteries and main buss bars. This is also where all the conduits for the wiring for owner installed electrical and electronic gear will be terminated too. Yes, I know, this is a bit inconvenient for turning stuff off and on but really, how bad is it to duck through the shower for a switch, compared to the benefits of centralizing everything?

Also, with this approach, all the electrical stuff will be safe in the equipment bay from the splashes of salt water, that you so rightly identify as a risk.

Cabin Sides and Room Under The Side Decks

Eric: Looking at the outline of the housetop on Selkie, much of the working area of the galley and the settees are outside of it. I suspect that a 40′ boat is large enough that there will be plenty of room at the settees for this but it might be tight in the galley.

I have been in many galleys where I have to bend down to work over the stove or end up looking straight into a wall and can’t see the stove when I stand up. I hate to admit it but I have come to accept the gently sloped house sides that some of the modern production boats have. Structurally, I suspect that they are easier to design. They provide more room down below and a good surface to walk on while on deck and heeling over. Obviously this can be overdone and side decks can become much too small.

John: Yes, this is a problem on any boat up to about 50′. However, the problem is not as bad as you might think on deeper hulled boats like Selkie because the sole is lower (see plan). I think we can also raise the freeboard a bit without making the boat look boxy. Good idea on angling the cabin side a bit too. With all that we should have most of that problem solved. Of course, good wide side decks that are easy to move around on are sacred to both of us and won’t be compromised for the interior.

V Berth

Eric: The way that the V-berth is done on Selkie would likely not be very good for me, though I do think that this type of berth is the only way to get all of the features desired into this size boat.

At 6’4″, I have found that the only way to get into these when the end of the bunk is obstructed is to crawl in head first on my hands and knees then spin around and lie down. This isn’t too bad when I am alone but my wife definitely does not appreciate it.

Also, I find that I am trapped unless I wake her up and have her move out of the way. The simplest solution for me would be to have the entire aft end of the berth unobstructed so that I could crawl off the end. This space could double as a place to change, put on shoes, etc.

John: There are a lot of trade-offs to deal with here. Yes, you could leave the head of the bunk open to facilitate entry and exit, but that means you lose two lockers so you have nowhere to put your clothes, your pillows drop off the bunk all night—something that drives me crazy—and you have nowhere to prop yourself up to read. We will have to arm wrestle to decide that one.

Hull Form

Eric: It would be interesting to see how a hull form like Selkie would be updated for use today. I wonder whether extra interior space would emerge or whether it would remain similar. Looking at the drawing, several feet of boat in each end are unused both on deck and down below. They are obviously there for good reason but I wonder whether new understanding of hull forms means that we can better use the ends of the boat or whether boats that use the ends now are designed around an interior.

[John starts waving his arms and bouncing up and down in his chair…then upsets beer all over himself. After mess cleaned up, John, now sitting in rather strange position due to soggy jeans and puddle of beer in his chair, answers.]

John: Pushing the accommodation out to the ends? No, no, no, no. Oops, sorry was I shouting? [People start leaving pub for quieter venue, manager comes to complain.] Seriously, as soon as you go down that road you invariably start messing with the correct hull form for a good offshore boat, just as you mentioned, and break a fundamental tenet of the Adventure 40 ethos, or in fact any good design: No criteria will be allowed to intrude into the design that will have any negative effect on the hull form.

Don’t get me wrong, I’m sure we can improve on Selkie, particularly since her design was, I think, influenced by the IOR rule of the time—look at her stern. We can also, I think, make the Adventure 40 longer on the water than Selkie, since we don’t care about ratings. But even there, we can only go so far, because if we make her longer on the water that will make her displace more—bigger and more expensive—since it will result in putting more boat in the water by definition, unless we make the hull shallower.

The basics of water plane, beam to length, displacement to length, reserve buoyancy, and correct prismatic coefficient can not be messed with without substantial negative consequences for seakindliness and speed.

This is why Carina, Selkie, and the new (and old) Navy 44s, still kick ass and take names every time they race offshore, and the tougher the race, the better they do. And not only do they go fast, their crews get where they are going in much better shape that those on light, wide boats that pound.

Can we distribute the hull volume in a better way than Selkie for our purposes in the Adventure 40? Probably, but we can’t create more volume without making the boat either less ultimately stable (lower ballast displacement ratio) or heavier and more expensive.

Yes, we could make her wider and shallower with a higher prismatic coefficient (fatter ends). But what happens to the boat then?

And what have we gained in terms of real usable volume? Well, a little if we make the keel lighter, but we have paid a big safety price and pushed the fuel tankage into the accommodation. Is it worth it? I say no.

Finally, the empty ends of the Adventure 40 can and will be used for storage, at least of lighter items, since one of the great things about Selkie’s kind of hull form is that, due to clever use of reserve buoyancy, it is surprisingly tolerant (within reason) of weight, even in the ends.

Having said that, I think that we might end up with a bit more space aft than in Selkie. But no way should the stern be a lot fuller than the bow since that leads to rounding up and bow burying.

We may also be able to get a bit more volume in the hull by flaring the topsides out a bit like Boreal do. Not sure of the trade-offs here—need to do more research.

Dinghy Storage

Eric: The other thing that I think needs to be considered when thinking about ventilation is dinghy stowage on deck. Since a dinghy is not included, this is a little bit hard but there should be an area where a dinghy can be placed without compromising ventilation.

Taking Selkie’s layout for example, there are multiple Dorades up forward as well as a big opening hatch so you probably would not want a dinghy up forward and you may even be prevented from having one with the dorade boxes. Between the mast and the aft end of the spray cover, there is about 6.5′ so that isn’t long enough for anything other than a nesting dinghy.

John: Good point. We are only planning for one Dorade forward so it should be possible to arrange the foredeck so that a smallish inflatable can be stowed over the hatch and forward of the single Dorade when coastal cruising.

We do this on Morgan’s Cloud and find that a surprising amount of air comes in if we just crack the hatch under the dinghy. Of course if you want to rig a wind scoop, then you need to dump the dinghy over the side.

When offshore, a dinghy should never be stowed forward of the mast. It should either be a nesting or folding dinghy stowed aft of the mast, or an inflatable stowed below. The current practice of stowing huge RIBs forward that cover the entire foredeck is just plain dangerous at sea and should be discouraged.

John Summarises

It is important to note that each time Eric mused about something he would like to see changed, he also identified the potential problems and trade-offs. This is the kind of thinking that is all too rare but leads to good boats. (You can read the full text of Eric’s comment, which I edited down a bit, here.)

For me, one of the big problems with modern yacht design, perhaps the biggest, is that too much emphasis is being placed on trying to ameliorate every little inconvenience of living on a boat without thinking about the consequences.

For example, if we end up with a V-berth, which is generally the only way to get a proper sized double in a boat this size, at least without making the bow too fat, the crew will experience all of the inconvenience and awkwardness that Eric identified or those that I identified, or a whole different set that come with an offset double.  But does that matter? Not much, maybe not at all. Not if the owners get to live their dreams in a safe seaworthy boat they can afford.

Bottom line. You can’t take all the comforts of home with you in any reasonably sized boat. And if you try, you will end up with a lousy, and very likely dangerous, boat—it’s your call.

“Compromises, Compromises.”

The wording that I imprinted on the plan of Selkie for this post is what my good friend Michael Haferkamp, owner of the beautiful custom Hutting 54 Polaris, always says, with a rueful shake of his head, when he and I discuss boat design.


If you want to comment on the specific compromises that Eric and I “discussed”, by all means do so as long as you keep the fundamental practicalities of a boat that must not get bigger than say 19,000 pounds in mind. But I would be most interested in your thoughts on the compromises you have made to make your boat work.

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Larry Jensen

Nice article, especially important to me as I am searching for my first Liveaboard/sailboat. I mention both as I’ve been coming across many nice liveaboards that can/should never leave the dock.

The idea of living on a boat (to men anyways) is to actually sail her. So understanding the tradeoffs of one feature over another is very important and that bring me to my question.

I’m looking at 38-45′ boats. As I’m 6’4″ I need a lot of headroom below and proper sleeping arrangements for both while I am in a slip and then also underway. I come across boats with great Center Island Queen Berths that are perfect for being in a slip, but once underway, the settees are too short to accommodate my length and while I’m not an experienced sailor by any means, I don’t think sleeping in a large open centerline queen bed while out at sea is a good idea.

So my question is this…when space is such a rare commodity, why do we put in two showers? I can understand why you may want two heads (in case one breaks down) but showers? I see many that have simply converted their second shower to a hanging locker. I to would use it for this purpose, but there is tankage and plumbing space that’s being wasted as well.

Second part of my question is location. In an efficient home design, we try to keep all plumbing close to each other. Why isn’t this don on a boat? A back to back head going to one central holding tank, even if you use to lines, you surly be a space saver along with not having redundant systems spread out on the boat.

Marc Dacey

Two heads are a direct result of the lubberly equation of “more plumbing means more luxury”. I would rather have one “pass-through” head with one set of plumbing runs and a bucket as Plan B. So many boats are clearly dictated in design terms by replicating (at dock) a sort of condo for hobbits. If I have guests on overnight sails (as crew, naturally), they make due in sea berths, hotbunking if necessary. No attempts, aside from the civilized practice of sundowners, are made to reproduce shore side amenities.

Attempting to do so is contrary, in my view, to the realities of life at sea. It’s why I have no V-berth on my steel boat: a workshop in a place in which it’s problematic to sleep while underway makes far more sense and yields far more space if you keep the heaviest tools and spares mounted on the collision bulkhead and light stuff forward under the chain locker.

For an ocean-going small sailboat, you want simple, robust and well-situated accommodations and facilities that will usually be slanted 20 degrees and prone to bouncing. I do not see these realities accounted for in many modern yacht interiors, which I assume is part of the rationale of the Adventure 40 project in the first place.

Mark Worrell

Hi, John

When you say “I would suggest that you not worry too much about headroom since setting that one criteria may push you away from some good sea boats that would otherwise meet your needs” I wonder if there’s a practical threshold regarding headroom in the galley, saloon, and cabins? For example, my son is 6’5″ and a lot of boats I’m interested in seem to ‘top out’ at about 6’6″ feet in the saloon and maybe 6’4″ in the galley (or less). I realize that there’s a big difference between moving about while docked vs. while sailing but where should I draw the abstract numerical line, or, conversely, am I just worrying about something that will not make a difference in the real world? Thanks!

Mark Worrell

Thanks, John, I’m learning much!


This is a classical Interior design that Hallberg-Rassy have been building for many years.
There is one major mistake. And that is the lack for, under the bunk storage in the salon. It is not fun to stand on your head in the V-cabin looking for that particular can of food when the boat is beating in to the wind on a long passage. My advise is to re-locate one of the water tanks to the V-cabin in order to free up space under one of the salon sofas.

You could also make a L-shaped sofa on the port side in the salon. That would increase storage and make the salon more appealing/comfortable.
Then the big cost saver. Why not a tiller instead of the wheel?


As you might know I own a HR 43. In the aft Lazarette we store,
4 fenders, 1 x 12 l Scubatank. 20 l of antifouling, spare anchor line 50 m, emergency tiller, Outboard oil, 8 mooring lines x 8 m. 2 x 10 l of fuel for outboarder.
12 kg of lead for diving. That is a little bit more than what you did see on the Boat Show;-)

In the saloon there is 6 over head storage lockers. Depth 44 cm.
SB side saloon sofa is empty for storage. L-part in the saloon is also free for storage. Behind both backrest there are storage.
John I do not agree with you ! Not many boats have that storage!

The two showers and heads:”Why build the best boat if no one wants to buy it?”.

But back to your boat. Why not free up one bunk berth for storage by moving the water tank to the V-berth?
Some experts say not good with weight up forward. But storage space will be filled with heavy stuff. Water you use. With some water management you could start to use the water from the fwd. tank and when that is empty switch to the tank in the sofa. This is better weight distribution then storing heavy things under the V-berth.


I think you misunderstod. I agree that the A40 is a typical one head boat. ( The HR 43 is not)
(Storage space. No there is only two versions. I have the smallest. But you have to get down on your knees to see how much space there is)
Good Luck with your project.

Robert Reyes

Engine access : Pacific Seacraft solved the problem by having a removable cockpit floor ; together with companionway access everything is accessible.
Why re-invent the wheel?


Robert Reyes


I agree with your later point;
However with a properly gasketed and secured hatch I think water ingress could be eliminated.



I’m up against the same trouble in my 32′ sailboat: poor engine access. A panel at the front of the engine, and behind the companionway stairs is completely removable, and there is access on the starboard side through the cavernous cockpit locker (no quarter berths) Alas, this requires a fair bit of contortion. I chose to install a Freeman hatch in the cockpit sole (not done yet, that’s this summer’s project) underneath the removable teak platform on the sole. This will obviously not be done while in heavy weather. I’ve read nothing but wonderful review on these hatches. Seals are replaceable and long wearing. Just a thought 🙂
It’s certainly not an ideal situation, but sometimes you have to work with what you have.


La conception de ce bateau présente des aspects originaux, et d autres fonctionnels, sur les plans de coupe la position des réservoirs en fond de cale abaisse le centre de gravite du bateau, ce qui donne par le poids du liquide GO au point le plus bas du bateau une meilleure stabilité, reste a connaitre la surface de la voilure pour calculer le ratio
L agencement intérieur est classique avec des points d originalité fonctionnels tels que : le couchage en V sur les flancs de coque , la position de la salle de bain, le moteur avec visualisation latérale et possibilités d accès aux pièces mécanique améliores par rapport a des positions classiques ou souvent les accès sont difficiles , c est un point positif important cette conception pour les longs voyages des navigateurs confirmes , Ce bateau en conclusion mais j analyse que sur plans me semble un excellent compromis avec la plaisance classique ou le confort est présent et les grandes navigations ou la réflexion porte sur les cotes pratiques ( Accès pour réparation , maintenance des installations ce bateau pour ce que j en pense a été conçu par de vrais architectes marins
je renvoie si je suis lu par ces architectes a mon blog ( hanse ) et qu ils comparent mes analyses concernant le constructeur HANSE ce serait intéressant qu ils analysent mes observations de ce constructeur naval en toutes objectivité technique
Cette article m a particulièrement intéressé dommage que ne puis visiter ce bateau
Bonne reussite a ces 2 architectes et comme on dit en France bon vent aux futurs utilisateurs D Faivet ( Ulysseempuria s ur facebook )

Eric Klem


This was fun to read.

As you said, it is all about compromises. Another way to put it is everything on a boat is affected by many other things so each component cannot be designed in a black box, it must be designed as part of a bigger system. This is where I think that CAD can be so helpful to designers because they can experiment easily with making those tradeoffs and they can design things in parallel much better.


Simon Wirth

Hello Eric
Steve Dashew demonstrates this nicely on
A lot of good pictures and explanations.
Thanks for the “talk” with John, it was very interessting. Have yet to find someone pointing out the reasons for compromises in sailboats as clearly as the two of you did here.
Regards Simon

pat synge

I query the categoric statement that “when offshore, a dinghy should never be stowed forward of the mast”.

We have a relatively long foredeck and carry an 8 foot aluminium dinghy (with flotation tubes) securely lashed in chocks. It becomes a useful brace when moving about on what would otherwise be an open space and the lashing lines are useful handholds. It allows us to have a forecabin hatch open in many conditions when this would otherwise not be an option. What’s the problem?

When discussing design you have appear to have ruled out the flush deck option despite the many advantages that this offers in terms of internal volume (and reserve bouyancy when heeled excessively).

And why can one not simply have a removeable gasketted panel in the shower stall that provides access to that side of the motor? Most motors have one side that only requires access very occasionally. If you have good access from the other three sides then this shouldn’t be an issue.

Switch panels can be close to the companionway if they have appropriate protection from spray (eg a fold down acrylic panel). Especially a companionway that is to be so well sheltered.


I presume that when pat talks of a flush deck (s)he is talking of the cabin roof height being taken laterally to the gunwales, completely eliminating the (need for adequate) side decks, as pedestrian access is over the top, and the rails/lifelines also take this path.
It looks great too.
Is there a fundamental problem with this design? Surely not as Jay Benford uses it.

Marc Dacey

John, this may have been covered in another post, but given your feelings on the placement of dinghies aft of the mast, do you have similar thoughts on the location of the liferaft valise or canister? Some go for “the high point” by the mast, while others opt for a strengthened spot on the stern rail or in that area. Still others will opt for a cockpit locker, but in light of your dinghy stowage views, where is your life raft and why did you choose to put it where you have?

It pertains to this discussion because I could easily see a design modification where the propane locker was “built in” on one side of the stern, while a liferaft locker (based on, say, an average of the top three valise-style dimensionals) was on the other side of the stern. I don’t know how or if that would increase complexity or price, however.

Dick Stevenson

Hey all,
The reliability of head toilets has come up here and other areas as a reason for 2 heads. Marc suggests a bucket as plan B. I would kick that to plan C. A Raritan PHII has been our head for 11 yrs of live-aboard use. Not often have we needed a plan B, but when we have, they sell (and we have as a spare) the complete working parts/assembly as a one piece swap: 4 bolts and a couple of hose clamps and you are back in business. Pop the offending assembly into a plastic bag and re-build it at your leisure. (Raritan will also re-build it for you.) Other toilet manufacturers may have similar systems. We do the re-build ourselves and have been rotating in re-built assemblies for years now which we try to do once a year so we do not have to do it under duress.
Dick Stevenson, s/v Alchemy, St. Petersburg, Russia
Ps. A great tool for clogged pipes etc. which will save a huge amount of cleaning is moldable aluminum pans in various sizes, I call them meatloaf pans. They can be molded and cut, and with a little duct tape can get below hose connections to catch the yucky stuff before it spreads everywhere.

Marc Dacey

I think a Raritan PHII is a very good choice…pretty well anything endorsed by Peggie Hall seems to work well over time. I would have one, except that the boat came with a Lavac, the presence of which impressed my wife so much she agreed to the purchase of the boat!

Patrick Synge

Hello John and all.
We obviously agree about motor access via a hatch in the shower stall ( I don’t know how I missed that!).

I suggested an acrylic protective screen in front of the switch panel if the most convenient place to locate it is somewhere close to the companionway. This could obviously be a completely watertight “hatch” if considered necessary (it would only need to be closed very occasionally after all) but locating it elsewhere may be simpler.

Dinghy stowage however is something else.

A cruising boat needs a good sturdy dinghy. For me this has to be aluminium with flotation tubes. An form of RIB if you like. The dinghy should always be ready to use so this rules out the nesting dinghy option. Try assembling a nesting dinghy when aground and heeled over and needing to row out a kedge as quickly as possible! I think we can all agree that davits are not suitable for serious offshore sailing aboard a 40′ boat. Few boats of this size will have space for a rigid dinghy between the mast and companionway without impinging on the vang and/or boom brake.

And what about visibility forward?

So where does it go if not the foredeck? I agree that it is a relatively exposed location but do not agree that it cannot be appropriately secured. On our boat we have welded attachment lugs that locate the dinghy exactly in place. It is lashed directly to these with Dyneema and cannot move without breaking these lashings (unless, of course, it is smashed itself). It also has straps over it to spread the loads (and to provide handholds for moving about deck). The dinghy virtually mates with the deck and so water hardly gets under it.

Effectively sophisticated “lashings” hold your mast in place why can’t they be relied on to secure a dinghy! I considered designing the foredeck with a dinghy shaped “cabin trunk” that the dinghy would fit on top of to provide it with extra support but decided against it. It might be worth incorporating reinforcing struts within the dinghy when not in use to protect it against crushing. On another boat we had a plywood dinghy that was smashed to pieces by a wave (it was on the cabin roof!).

As I mentioned in my previous posting we have a relatively large and unencumbered foredeck and far from being an impediment to sail changes I find it helps to have something to brace myself against (or shelter behind) if I am having to work in a crouched position or on my hands and knees.

Weight and windage distribution is another consideration. Moving the weight forward and down may or may not be relevant. As for windage this is probably only relevant when going to windward and, when heeled over, the windage of a dinghy on the foredeck is fairly minimal: possibly less than having it on the cabin roof where it is more exposed.

It will take some pretty strong arguments to convince me that there is anywhere better to locate a decent rigid dinghy on any boat under 50′.
Over 50′ I would consider a ‘garage’ built into the stern. But then I probably wouldn’t seriously consider a boat over 50′ for shorthanded cruising so that’s entirely hypothetical


Hi John,
What about a large stern locker like the Boreal has? I realize the A-40 is four feet shorter and narrower in the stern but still with the great inflatables that are out there today one could easily design a locker that an inflatable can be stowed in for passage.


The ultimate container storage system?


Hi John,
Jimmy Cornell’s new boat provides an interesting contrast to the long discussion about desirable characteristics for a long distance cruising boat. While it is bare aluminum, it is almost the diametric opposite of yours and most contributors choices. Triangular in hull form with the widest point near the stern, shallow draft centerboarder, with a trunk cabin resembling that of a Lagoon catamaran.

Keith Jones

3 of the old design Navy 44’s are at auction now,

Keith Jones

Had trouble making that link work. Try

Then hit Boats on left hand side. You can put Navy 44 in the search to find the 3 boats.

Ee Kiat Goh

Hi John, Pardon me if I am posting this in the wrong part of your website as I find this to be the best fit for it. Weight distribution on cruising boats. I have added a beefy davits, a dinghy on the davits (for coastal sailing), 4 solar panels, a radar, a wind generator, a life raft and a 18hp outboard. I notice that the boat is pitching up at the bow. Is it a good idea to add more anchor chain at the bow to pitch it back down? How does weight distribution inside a boat affect sailing and stability. If i have to add ballast, where would be the best location? Overall, my 46ft boat (36ft LWL) is on the lighter side (18 tons) compared to other sister boats (20 tons).