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Hallo, im a unknown Beginner. I can buy two unfinishd hull here in the Philippines from a local boatbuilder. I start to make plans to finish the cat. but i have to add and to build the Beam. i saw some pick´s in this forum of building some alternativ Beam. i dont have the plan of the Tiki beam. so i need a alternativ for that.

here i have my drawings for the 3th where the mast should be and the 4th beam where the Helm and cabin will be.

Plz can sombudy of all this profesional builder in this forum give me some advise if i wrong or good with my planing or to much or to low. thank u so much for ur help.


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Surely the builder of the hulls will have the plans?

Hey there Andreas,

If the plans are unavailable from the builder send an email to Wharram Designs, (wharram@wharram.com), asking for what you need and advice on any changes. They will help out, reply time can sometimes be slow but they will get there.

Good luck.

Hallo Paul, Shaun,

the builder is a local boatbuilder who build boats for more than 30 years. the two hull r build in the typical Philipino style. 13.50 long , 1,83 width and 230 high. without bulkheads and deck. so i think i dont need a buildingplan for that tyoe of boats from Wharram. even i dont need permision to finish some like that type of boat from Wharram. coz his style of boatbuilding was never invalved in this building. The boatbuilder is alocal person who never knows James Wharram and never has listening some of him. 

So much for explane the situation. 

never mind, im not against James Wharram and his boatbuildingplans. but i think for a local boattype i dont need to contact him. 

And the plan was to build a local catamaran, but the one who startet for that is out of money, and let the two hull stay. 

and now im intrestet to buy the two hulls and try to finish the local catamaran. all i need is a littel bit help for building the Beam. coz boatbuilder here just take some bamboo stikes and make a crossbeam of that. but i dosnt trust that style. so i saw the alternative beam in this forum and i start to think maybe some of all this near professional builders can give me some advise. 

thank u so much for ur reply. 


Hallo Demi&Dyke,

u have a very very nice Boat, i have look many pickures of ur bat already. especialy for the longshaft engine and also for the beam constructing. But the problem is not to build the beam in that style, the problem is the dimesions. i dont have any idia how big, high and width the beam should be so that they r strong enough to carry my Mast, engine,on the 3th beam and the little cabine with the helm on the 4th and 5th beam. Maybe u can give me moore advise????

thanks for ur reply

Andreas, ANDY


My advice is to be VERY VERY careful if you plan to mix different styles and construction methods.  A Philippine style boat with no bulkheads and no deck will move and flex in a completely different way to a Wharram.  The structure where the beam loads transfer to the hulls will be very different.  Wharram beams suit the hulls they were designed for but might not suit the boat you are looking at.  I would not do what you are suggesting, but if I did I would pay a professional designer to analyse the structure and design the beams.  He would need a lot more information than you have provided here.

Ask yourself why you don't like the beams used by the local boat builder who has more than 30 years experience.  He ought to be the best person to know what works.  Bamboo is a wonderful engineering material.  If it's just that you're not familiar with how to work with it get advice from the expert.  If you really don't like that type of beam consider getting a secondhand Wharram instead, there are always plenty around.

This is just my opinion.  Others will think differently, it's up to you.

Regards, and good luck whichever way you go.

Rob H

Hallo Robert,

thanks for ur advise. U r right, im not familiar with the material bamboo. they use it here allover in the boat construction. my plan is to add bulkheads and sure a deck. The boat hulls a made of a mahogany frame without bulkheads. but its easy to add tham coz no deck. even no interior is fix already. so i have just the hulls. my plan was to com near for the wharram style boats. also the cat will be use only here in this area to drive for other beach or go snorkeling in our bay. so no long distance driving.

here the boatbuilder also just use two hulls of normaly Bangkas around 10 meter long and put tham together with bomboo as crossbeams just to go out for fishing. after return from that trip the get the bamboo and each fisherman get his own boat back. style of the hulls r the same. just mahogany frame with ply. no epoxy just paint. and the hulls r not more than 2 -3 feet width and 2.5 feet high. the keel is one peace of wood and flat bottom.

ok i truly get ur advise and be very carfull with what im planing for. thanks ur reply.


Ahoy Andrea,

     You can look here if you have the time:

http://www.spc.int/coastfish/en/publications/posters/boat-plans.htm... \

It sounds like you have local design, not Wharram, but you might find something applicable on the link.  Some searching is involved. 

     Your drawings look nice, but don't match anything I've seen yet. 

     Are you mounting the mast on the beam or what rig are you going to use? 

     You can find a lot of information in the links on the wharram site to the sailorman and sea people magazine.

     Please post pictures, if you can, of the hulls.  It's a lot of fun to play around with ideas, but when you actually build something, you have to deal with reality.



Hallo Andy,

Thanks for the link. Yeas u r right, i have a local design and local boat builder who use his own design.

he has build already catamaran with cabin. Like cabin cruiser u can see allover. when i show him the picktures of James Wharram designs he dosnt know. But the two hull what r staying around in his yard, its easy to add bulkheads and a interior and than close the deck and truly add the beam. The must should stay at the 3th beam . This beam should haqve 40cmX30cm 720cm. my thinking was that the Beam should be at the center 40x30 and going to the end down to 30x30. Between the 3th and the 4th beam, who has the same size, is only a open bridge deck with sitting area . Between the 4th Beam and the 5th Beam should be the helm and a small cabin shower and Toilet. I will use Composting Toilets, its easy to handle it. Even in the Hulls r no toilets. I will use for each cabin one Composting Toilet. I know the easy handling coz of my Homecar i own before in Germany. If use over the daycruising, we can empty them in our Septictank at home. our house is near the future  mooring place of our boat. so no problem with that. Between the 5th Beam and the 6th beam is only open deck, maybe use for a dinghy. I like to use wingsail. even if need, we can add a second Mast like for a ketch or Yawl, on the 5th Beam. but im not sure to deal with. i think one mast and wingsail is enough. i also waqs thinking to use Electro Engine from Kreutler Austria, but really the price is so high of tham,around 7000,- euro each and i must import them over here to the Philippines, so i turned to one engine under the Tabel in the sitting area and make a longshaft like the Wakataitea has make. much cheaper and easy to handle here, also the repare if some goes wrong with the engine is easy for the local mechanic.so maybe that is the best way.

the size of the cat is 45' x 23' feet, 13,75 x 7,15 meter

Ok, a lot of information now i have give. I hope and think some of u can make already a pickture in his mind of my planings. actualy planings r already more than thinkings. i will come concret.

thanks for reply

Regards Andy

Nice drawing.  Layout similar to Tiki46.  Good idea to make a model and make any changes there before going ahead with full size build.  If you can digitize it and load it into Delftship, then waterline and immersion information can be quickly calculated.  This is important with a custom design.  I am the proud owner of a boat where all the horizontal surfaces, like galley counters, soles, everything, slants aft, and it could have been sorted out by the original builder by building a model and seeing how it sat in the water.

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