Design and build plywood fast cruiser with lifting keel, 36 feet

[Paul Scott]

Another lateral thought experiment, going to an older keel design notion adapted to fairly high performance catamaran, mainly to make a point that the notion works in high speed regimes, and fits, I think, with your desire for a more traditional approach:

Play with beam and length, add ballast and a centerboard, maybe. The Shark gets by without a center foil. You’ll need some technical advice for optimum long keel shape, but my main point is that the concept isn’t necessarily slow. ( I think a Finn style centerboard might work- even if the large racing designs that have used it date back a century…. some even used 2 centerboards longitudinally for balance). With modern build stressed ply techniques? (A (skinny) monohull of course….)

 

[Paul Scott]

Similarities? Add some modern tech, rudders not attached to the keel, and a centerboard that can extend farther without breaking…

CRUISING SAILBOAT EVOLUTION: Early Trends in Yacht Design - Wave Train https://wavetrain.net/2013/09/30/cruising-sailboat-evolution-early-trends-in-yacht-design/

 

[skaraborgcraft]

Crikey, that top boat has sections similar to those "cowhorn" boats.....but without the draft.

 

[Petr Podobsky]

I want to chime in with "circumnavigation-36feet length-fast/planing":
this will be VERY difficult to realize: even if you are a very frugal person & put up without all the "luxuries" considered indispensable on a cruising boat these days, the very light weight needed will be a challenge to achieve. Basically you will scale down a class 40 (which will only be fast of loaded lightly!) to 36', so the payload-in theory-will also be only 73% of the , already low, payload of the class 40.-If you want to achieve similar performances. Can be done, but will mean 1 T-shirt, 1 short, 5 rolls of toilet paper, 1 bicycle-multitool for toolbox,...this sort of "list".
36' & circumnavigation: imho you will have to go with "moderate cruiser/racer-type" & forget the "planing". You will still have to prioritize your "packing list" heavily. (fwiw: my "credentials" are 1 rtw on 34' Wharram cat, 2 rtw on 37' Pouvreau 11.30 & 1 France-Tahiti on Elan 410)

Yes as discussed earlier, she will be deffinitelly not planing boat. Just a fast cruiser. I have to charter some RM yachts, to get real immpresion.

There is a couple sailed to the north with RM 1050. Must be quite bumpy sail.

 

[ExileMoon]

Praise your great ideas！ Everyone should have a great dream, and then strive to achieve it.

If you want to quickly circumnavigate the world, a catamaran or a trimaran may be better, and you can also consider a PROA. Under the same construction cost, Proa can achieve maximum length and has a large aspect ratio, making it the fastest sailing speed. After the length increases, comfort also improves.

Under the same drainage type of hull, a 40 foot boat is at least 30% slower than a 40 foot proa, and at the same price, you can make a proa that is at least 52 feet or even 60 feet.

Compared to mono hull boats, although the construction cost may be lower, but the mooring fees may be higher for those type of boat. Because if charged by length, the length of those type of boat will be much longer than that of a mono hull boat; Charging by area is also the same result.

 

[CT249]

Yes. I want to have relativelly small boat with not too much expensive mooring costs. Wider boat also provide a lot more space which is also my requierement. I also see that wider boat is the current trend.

They have more righting moment. When the flat bottomed boat is not too much heavy and its heeled, the bigger part of the hull is lifted out of the watter and BWL ratio is getting better. Maybe therefore the flat bottomed sailboats are faster? Am I right?

I like your taste, but how important are reducing mooring costs as a factor in your whole budget? If you want all round performance then going longer but leaving everything else the same is an excellent way of getting it. Look at the J Boats or the even narrower Scandinavian style of boats like the Luffes; they are very different to the style you like and that's fine but it's interesting how modern marketing coming out of the big French companies seems to promote wide boats without presenting their drawbacks or the alternatives. Arguably the wide "French style" boats are just as much a creation of racing rating rules as any 1970s IOR yacht.

I'm not sure what you've sailed but that Feeling is not a particularly fast boat according to its basic dimensions, so if you found that fun you'll probably love a JPK style of boat. They look great apart from the linear galley, and that's a personal thing. JPK is a hell of a good sailor and that seems to make a huge difference in the way a boat is produced.

Wider boats are the current trend in Europe but why just follow a trend? Wide boats are, in general, slower upwind and in light winds because of their higher wetted surface and waterline beam. They have the advantage of greater stability but to use that greater stability you will impose higher loads on the rig and therefore have to increase rigging size, sail weight, spar strength, winch size, etc.

Whether the flat section of the hull lifts out of the water enough to reduce drag depends on the particular design. In heavier cruising boats the flat section may just stay in the water and drag. In rough water the flat section just above the water may get bashed by waves. Down here in Australia we often have an almost everpresent ground swell rolling in and often bouncing off sea cliffs to create a lot of chop even in light winds, and in those conditions the flatter hulls often do poorly because they get slammed around. In other places where the chop and swell drop when the wind drops, the flat hulls can perform differently.

 

[CT249]

Under the same drainage type of hull, a 40 foot boat is at least 30% slower than a 40 foot proa.

Is a 40' cruising proa really going to be about 15% faster than a Farrier F9A-XR, for example? When have 40' cruising proas gone up against a number of boats similar to JPKs or other multis? We all know that merely picking one example will not prove a general trend when there is as much variation as there is between boats and passages.

 

[Petr Podobsky]

I have been looking for some "classic modern" yacht past few days. As said before Berckmeyer designs are closer to my taste, but I think the bennefits of such a design will be not worth the costs for me. Classic wooden boat should be heavy and slow, or slim and long. Trying to combine modern and classic would result in some strange looking design. To build strip planked hull and spend a lot of time with all of the visible wooden details will add a lot of time and costs. Not smart. So some wooden details in the boat must be enough for me.

I´m going back to my initial idea with some little changes.
Basically the boat should be smaller plywood chined JPK 45. Dimmensions 12m lenght, 3,8 to 4 m width. How flat the hull will be? That is the big question. I do not want to create "Class 40" style boat. The maximum flatness of the hull will be something like RM/JPK yachts have. Something little more cruising/exploring oriented. Good performance upwind is also important for me.

Regarding to the lifting keel, I think it is possible to create keel bend/crack in designated place leaving the boat hull structure undamaged in case of accident. So the long, thin, electric operated lifting keel is the way to go for me. Located most likely in the middle of the saloon. I do not like that possition, but I do not know how to avoid it regarding to my other interior requirements.

Two aft cabins plus one under the main saloon sofa. No front cabin, just storage space and two folding beds or beds/storage. Two rudders and tillers. (love that) Hard transparent bimini.

She must be able to sit on keel and rudders.

To the winches possition I still do not know. I like the JPK 39 sollution, but most of the time the boat will be sailing on autopilot and It would be nice to adjust the sails from the safe place under the hard bimini.

I would like to make most of the parts steel/aluminium because it will save time and even costs for me. I mean, internal keel structure and keel (steel). Rudders, hard bimini, railing etc. aluminium.

I like the way the RM yachts are build because there is a lot of "dry/clean" assembly work and after that everything is on its place and checked commes the sticky/dirty job of laminating. Which is can be done by almost anyone. So the building method is set.

So I will draw some basic lines to verify mi ideas. Nothing final. Just to continue the idea.

 

[Paul Scott]

Something might amuse- 2nd 2 pics are the same boat, same sort of underbody as the line drawing. Sail plans optional. (I’ve lived with a forward swept high aspect fin keel for 25 years on a 40er with a d/l of 96, 8.5’ draft, and granted she goes upwind like metre boat, but there are some trade offs that you might consider vs the Irens approach below. She is a wooden boat, COVE construction, Steve Rander built, at Schooner Creek Boatworks ).

 

[tane]

...To build strip planked hull and spend a lot of time with all of the visible wooden details will add a lot of time and costs. ...
...Basically the boat should be smaller plywood chined ...

I am currently building a triple chine 22' plywood boat & am not sure, that combined strip-planked underwater-freeboard plywood would be much more work.
...the sticky/dirty job of laminating. Which is can be done by almost anyone...
Laminating the chines is in many places a careful job, as one wants to avoid any voids (sic!) in the laminate.
Hiring out the laminating will not save all that much time, btw. & NEVER forget: if you are not a professional, but a true "amateur builder", building a 36' boat, fully fitted out for living aboard & cruising is a HUGE undertaking, that will cost you much more than a second hand boat (& probably your marriage/girlfriend too). Think 5000 man hours

... Rudders, ... aluminium.
would be one of my last choices on a composite boat. Aluminium rudder only on an aluminium boat.
...

there was a builder in The Czech Republic a few years ago that offered aluminum 36' Van de Stadt "Fornas" bare hulls, IIRC .
Not a "moder planing boat" by any stretch of imagination, but very likely a boat with extremely good overall sailing performance (for a cruiser!), and-aluminium is my absolute favourite for a long-term-blue-water cruiser. FAR better than ply/wood/stripplank - no matter how much epoxy (the 22' I am currently building is ply/epoxy, but for reasons completely unrelated to the suitability of the material for a blue-water boat!)

 

[Petr Podobsky]

Maybe I should say, that I was working two years in composite boat building company.
So I can check if the job is correct. And I can train people, how to do the job correctly.

5000 man hours is right estimation I think.

To the price. I will build a boat that is not possible to buy or are very rare. The main reason is not to save money but enjoy the process.

 

[tane]

"...enjoy the process.

GO FOR IT!!!
(this is the reason for my current build too, & I enjoy every momentof it!!! The "extasy of creating" we say in Geerman