Is this project feasible ?

My project for which I plan to spend around 300,000$ is :

a 70' ultra light displacement monohull sailing yacht with a liftable keel and a Wing mast to simplify the rig.

Arrangement : 3 cabins (2 double and 1 with 2 single bed), one bathroom, kitchen, etc...

The program is fast cruising circum navigation in family with a possibilty to race during our stopover

Building : red cedar stripplanking for a lightweight one-built boat with a fiber glass layer outside, this will insure good insulation with beauty of wood strip for interior decoration

Thanks a lot for your criticism and your idea


I don't that

 

Is it feasible? Yes, although your budget sounds awfully tight for such a big boat. (Is that $ USD? does that include NA fees etc, or is that just the construction cost?) Are you planning to build yourself, or have a yard build it?
If circumnavigation is the plan, it'll be pretty tricky to get a very light boat strong enough to do this, at least on a tight budget.

 

I don't know if low WEIGHT and low BUDGET go together! You can get to a point that pounds cost exponentially more to lose.

I could be wrong, but I don't think an ultralight boat will give you very desirable cruising characteristics. But, if you place that weight smartly(away from axis of rotation), perhaps it wouldn't be so bad.

However, I really like the woodstrip idea. I've seen it employed on kayaks and despite all the advancements in plastic techniques and high-end composites, wood strip remains the material of choice for kayaks. Additionally, it's a relatively forgiving medium, lasts very long(with proper upkeep), is lightweight, is strong and is classically beautiful. The only disadvantage I can see is it can be quite time consuming to construct.

If it were my project- I would make it unsinkable with a FRP,woodstrip, foam, FRP(or KEVLAR)sandwich, and use a keel/centerboard for shallow water sailing.

 

My budget is in USD
It covers hull construction, interior arrangement mast and sails.
I have another budget for fittings and equipments (engines, toilets, kitchen, etc...)
It will be built in a boatyard in SE Asia to save money on labour hour cost.

Do you know if such boat plan already exists ? Name of the designers ?
Is there any architect well know for its stripplanking hulls ?

 

I think you might be approaching this from the wrong direction. You have so many unknowns, that it's difficult to balance all the variables.

I would rank your 'needs' as follows:
1) A boat for a fast cruising circumnavigation with the family
2) With 3 cabins (2 double and 1 with 2 single bed)
3) Preference for wood
4) A design that can be built in Vietnam
5) Light, rather than heavy displacement
6) Lifting keel if possible (although very expensive to build well)
7) Would like to race it
8) Prepared to think 'outside the box' to save money (eg, a wing mast, although it would restrict any racing I could do).

Next I would look at the Van de Stadt 'Tonga' http://www.stadtdesign.com/products/vds428.htm

Although it's not 70ft, and not strictly 'ultra light' it does everything else (including the lifting keel option) and is a known entity. It's a development of the Samoa which I have built for an adventurous world cruising couple and it's difficult to fault. It also has a wing mast option which is interesting.

Next I would buy the study plans. They are only 45 euros. These should be enough for you to start doing meaningfull research in Vietnam. What timbers are available (I doubt it's Western Red Cedar), what skills are available, what glues, resins and glass? You should be able to start getting realistic costings.

I would hazard a guess that it may be easier to have a cold moulded hull built using local veneers on laminated ring frames than sticking strictly to the idea of a 'strip planked core - epoxy glass' boat. This tended to be a method developed in the west in response to our high labour costs and ready availblility of epoxy and glass.

Then I would explore equipment and sails outfitting. Do you motor the outfitted hull up to Hong Kong and rig her there or try to build / obtain something locally. Lots of options to explore.

Then once you have fully costed this 'bench mark' design, (45 euros and a lot of your time and effort), you can then deside whether you need (and /or can afford) to go bigger and lighter. You may find that the Somoa will also suit your needs. Forty seven feet is still a big world cruising boat, but only about one thrid of the size of a 70 footer and half the price.

Remember for the cost of a plane ticket to Europe you can sail a Tonga with the Swing rig. If you commision a design (in which case I would like you to consider ME!) you will have to bear all the cost for developing a design and you will build the prototype. Not usually the recommended thing when you have a limited budget and want a 70ft boat.

 

For 300,000 You can not get this boat even in Vietnam...
P.S. Never save on plans - they should be good for reasonable cost. Otherwise filally You pay double for construction.

 

Crag Cay,

Could you explain the difference between traditional woodstrip contruction and the method you propose?.

Or perhaps, for clarity, I'll explain what I mean by woodstrip: Woodstrips faired across wooden supports(not sure what you'd call it but it's essentially the male version of a basket mold)sandwiched between two layers of FRP and varnished to a high sheen producing a lightweight, longlasting, strong, but labor intensive construction.

 

Yes, woodstrip and cold molded do indeed cover a variety of techniques going back over many years.

The one you describe isn't infact 'traditional woodstrip' but a more recent variation. It's perhaps more accurately called strip wood core FRP sandwich and is described here: www.stadtdesign.com/English/history1.htm Essentially the wood is acting like any other core in sandwich construction, except it does have some inherent strength of its own, especially in a longitudinal direction. It's obviously not quite as light as foam or balsa core, but has several compensating advantages principally that you only need a simple set of transverse building frames as the wood strips take on a fair curve, and the strips are quite quick (and easy-ish) to fit. It does however require coating in glass on both surfaces with epoxy glass.

There are a number of variations on this theme, where more framing or bulkheads on the inside can replace the inner glass layers, etc. This makes it more akin to 'traditional strip planking', where thin strips of wood were glued and nailed to a more conventional system of frames and stringers. This was quite a common way of building small one-off race boats in pre epoxy days.

Cold molding is where wider strips of thin veneer are lamininated together, (usually over a more sophisticated building mold than with strip planking) to build the hull skin. The first layer goes on at 45 degrees to the centre line and the second at 90 degrees to it, with the third, (on larger boats) running fore and aft. Each strip of veneer has to be shaped so it lays flat and closely adjacent to the one beside it, and are usually stapled to the layer below to compress the glue. A fine method that can be successfully done without epoxy, but requiring much more skill at both the set up and building stages.

You can also get hybrid variations where a lighter strip planked hull is coated in glass and is then covered with cold molded veneers and finished bright.

All these methods produce decent boats, and have been used successfully from canoes up to square rigged ships (STS Tenacious).

So you have to weight up your options: If your lumber mill can rip you nice thin wide veneers of a mahogany like timber, and you have a good source of skilled (cheap) woodworkers, then a cold molded hull should be considered. Especially if a ready supply of unidirectional glass and epoxy is difficult or expensive to source. However if these materials are easy to get, and your lumber mill can produce dry, well formed profiles in a lightweight, stable wood, and your labour is more enthsiastic than skilled (or just expensive) you may be better off choosing some variation of strip planking.

 

Cruising boats should be strong comfortable homes. Racing boats need to be light highly stressed over rigged speed machines.
Then you mention family.....have you heard of the Comfort factor ratio ?

That said, your philosophy sounds like that of the Dashew's I think the latest design is called Beowolf have a search for it.

But I'd try a week on such a vessel before I considered buillding one. It's easy to fall into the trap of producing a boat that is neither a comfortable cruiser or competitive racer.

Good luck

 

From Steve Dashew's website: "Sisterships to Beowulf are available for around US$4,000,000 depending on final specification and exchange rates."

I don't think any final specifications or exchange rate fluctuations are going to bring it down to 300K.

 

You could probably buy an old Santa Cruz 70, they have a reasonable accomodation, I remember an Alan Andrews 70ish long performance cruiser also that is abit more cruisie. They may not be the "Ideal passagemaker" but they are fast, fun and easy to sail.

 

The design philosophy can be learnt from. That was the point.

 

Crag,

The Cold Molding technique you describe seems similar to the technique used to produce this boat:

http://www.enavigo.hr/en/

Essentially, they use the thin woodstrips epoxied together over a simple building frame to supply the frame. Then they lay one layer of wood from one side of the hull to the other. On top of that, they lay two layers of wood at 45 degree angles to each other. They glass over top of this to complete the hull.

It seems almost like too much wood though. How do they bend the wood into such narrow arcs. Couldn't a suitably strong hull be created simple by using an FRP/Strip/Kevlar strip wood core? Could a foam layer be added without much alteration?

Sorry if this is a threadjack, I'll start my own thread if you like, Trimix.

 

Here ya go. I saw this listed for $375,000.00. You could not build it for that.

 

You mean something along these lines:





Check out http://www.parker-marine.com/brokerage.htm