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I have built several boats from Marine Grade Aluminum I very much like the Pahi 42 desine .    I do not like the idea of dagger boards,  I prefer the small keel on the Tiki desines .I was hopeing to recieves some of your thoughts on this idea . Also I have only found very little information on building a James  Wharram desine in aluminum,   just a few photos of one vessel on the internet any more info  information would be very help full.    I just purchased a new miller welder for wellding aluminum Wow it makes welding aluminum so much easyer than in the past ,   the auto settings are great .   I love building in Aluminum very fast. so light. easey to work can be cut with woodworking tools .   no painting sanding , only need to paint the interior ,   very good tensile strength many of my friends build aluminum river boats one hit a larg rock at 25 mph crumpled the bow but it did not leak he just cut out the first 4 feet and welded a new bow , I was amazed.    Some grades of aluminum are close in strength to mild steel , thank you for your interest on  this subject .

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Hey mate i was speaking to old fella here in Aus. the other day,he was a commercial fisherman who had built a wharram,not sure which mark out of aluminum. It can and has been done.How you would go with the complex curves in that material I am not so sure.

Thank you for your reply the photos I found online I believe they are from down under ill try to down load them here 

Other than converting the wood scantlngs to aluminum, the build should be straight forward. The Wharram Tiki and Pahi hull designs are basic in that they don't incorporate any compound curves too complex for plywood. Additionally, unlike aluminum, plywood cannot be bent in two directions at the same time. The aluminum can be deformed to duplicate compound curves. However, for its weight, it's hard to beat good marine grade plywood. I'm not convinced an aluminum Wharram hull, built to the same specifications for strength, wouldn't be heavier than the plywood hull.

I'm a wood boatbuilder and I like wood. An aluminum hull would still need to have an interior made, and all the myriad tasks required to complete a sailing vessel. I don't think the total build time would be greatly improved on a one-of boat.  Not even sure how much more durable the aluminum hull would be in the long run. I recall seeing an aluminum power cat, a former U.S.Army Corps of Engineers boat, that had endless electrical issues because of the aluminum hull.

Omar

http://www.trademe.co.nz/motors/boats-marine/yachts/multihull/aucti...

follow the above link. Aluminum Wharram for sale.

thank you this answeres many of my questions



Alfred Archibald Linthorne said:

the aluminum hull is not causing electrical problems it the lack of isolation of the electrical system.    thank you this amswers so many of my questions 

Actually, that's only part of the answer. Even in an aluminum boat, with no electrical systems, any metal in contact with the hull, except for aluminum, zinc, or magnesium, will cause the aluminum hull to corrode. More info is available here- Aluminum hulls

Omar

yes disimular metals are also a problem these solutions are well known hopefully by now there is a lot of info about sacraficial  anodes even many diesel engines have anodes in the raw water passages

I just priced out the cost of plate aluminum for 50 sheets 5ftx12ftx.250 in  6061 aluminum is 30,000 Canadian dollars  enough to build 2 complete 40 ft hulls in aluminum this is high tensile material this is looking better all the time any thoughts ? 3/16 is about 25 % less also 25% lighter

 

This aluminum hull might just work as a hybrid (using timber and plywood on the topside`s and deck; if you take inspiration from the original Polynesian Pahi.

This is what I have done by using a resin/glass composite for the bottom part of the hull structure and extending with wood after the fashion of the Pacific Pahi.

By using  welded ally plating along with round bar (keel) and tubular longditudinals, it could possibly achieve something similar and without the complexity and added weight of  fitting out  aluminum hulls with a light wooden interior..`

"...enough to build 2 complete 40 ft hulls..." Does this include stringers, bulkheads, decks, coach roofs, interior furniture, and welding materials? If so, your aluminum costs are comparable to ply/lumber/epoxy construction of two complete hulls.

There are other considerations with aluminum construction: Foam or some other insulation is a requirement rather than a want, and adds to the costs. It is also likely that woods will still be required for interior furnishings, further driving the total costs up. Zincs and galvanic isolators are also required. These are not things that should prevent construction in aluminum, but considerations to overall cost of a build - that is if cost is a consideration at all.



Alfred Archibald Linthorne said:

I just priced out the cost of plate aluminum for 50 sheets 5ftx12ftx.250 in  6061 aluminum is 30,000 Canadian dollars  enough to build 2 complete 40 ft hulls in aluminum this is high tensile material this is looking better all the time any thoughts ? 3/16 is about 25 % less also 25% lighter

 Yes this includes 2 complete hulls with material left over these sheets are 5 ft x12 ft have not priced masts yet but tapered flag poles made of  hi tensile aluminum 6061  35 ft are about 2000 Canadain dollars each 8" on the base 4" inch on top     3/16" wall  still researching beams .

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