Materials Advice for a 18' Power Catamaran

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Catbldr
Posts: 21
Joined: Sat Jul 08, 2017 8:59 pm
Location: Nags Head, NC

Materials Advice for a 18' Power Catamaran

Post by Catbldr » Sat Aug 05, 2017 12:02 am

I was going to build the Hell Cat but decided to go to the Aqua Cat. I figured if I'm going to spend the time I'm going to do it right. This boat will be out in Cape Hatteras area. Lots of Sound running and some near shore ocean fishing. It will take some pounding. I am planning on doubling up the transom to two 3/4 inch sheets of plywood. 3/8" aluminum mounting plates for the engines will be installed. All the frames will be Marine grade Douglas Fir plywood with white oak members. All the longitudinal members will be white oak as well. The plywood hull will be scarf joint Okuome plywood as the wood is readily available and at a pretty good price. The only place where a butt block will be used is the tunnel. The tunnel and hulls will get biaxial glass ( one layer only ). The sides will get one layer of glass as well as I would like to keep the sides clear. The biaxial glass will go up the outsides of the hulls about 4 inches above the waterline where it is painted. The inside will get 3/8" plywood deck and 1/4" sides. I am going to foam the hull. It will be powered by two 60 or 75 hp Yamaha four stroke engines, hydraulic steering. The cabin will be eliminated and a center console will be used. Twin fuel tanks will be mounted in the hull under the console. T-top will be added, Aluminum and soft top.

So what do you think of this scenario? I want this boat to last. Maybe my son will use it when I'm gone. Who knows? I respect everyones judgment and I am new to this so you won't hurt my feelings. It's a big commitment and I want to do it right. If I need more power for the weight so be it.

Cyclone
Posts: 62
Joined: Sun Jan 08, 2012 7:26 pm
Location: Barrie, Ontario

Re: Materials Advice for a 18' Power Catamaran

Post by Cyclone » Sat Aug 05, 2017 4:29 pm

I think what ever boat you build if you are using materials and thicknesses listed in the plans then no concerns. I like using white oak although if you do some research you will see there are some concerns with gluing while oak and some precautions that can be taken. I would recommend getting quarter sawn material if using white oak as this gives you the strongest and wood and less subject to warping. I like the Aqua Cat. I understand you are going to use your boat on the ocean and I think the Wildcat EXT Sport would be a better choice as it has a deeper hull and there is a 20 foot length option in the plans which is only 1-1/2 feet longer that the Aqua Cat. I think the deeper hull would be better for the ocean. Also look at the hull depth between the 2 hulls on the pictures they provide with the information on the Aqua Cat. It looks hull depth there is not very deep which appears to have been designed to maximize cabin room. I think for the ocean, or larger waves on a lake, a deeper hull at the center between the hulls would also be better and since you are talking about eliminating the cabin you do not need the shallower hull depth between the hulls for cabin room. The Wild Cat EXT with the 20 foot length option is designed without a cabin and the open area you desire.

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Catbldr
Posts: 21
Joined: Sat Jul 08, 2017 8:59 pm
Location: Nags Head, NC

Re: Materials Advice for a 18' Power Catamaran

Post by Catbldr » Sat Aug 05, 2017 9:32 pm

The Wild Cat is a "whole lotta boat"! It is gorgeous. I think I'll stick to the 18. The power upgrade alone is probably a budget breaker. Outboard engines are getting soooo expensive. Hard to find used twin sets. The ones you find are 250 and 300 hp.

Jeff

Cyclone
Posts: 62
Joined: Sun Jan 08, 2012 7:26 pm
Location: Barrie, Ontario

Re: Materials Advice for a 18' Power Catamaran

Post by Cyclone » Sun Aug 06, 2017 6:50 am

Jeff,

I understand your concerns about the cost of out boards. There is some overlap on the recommended total horse power where the Aqua Cat's top range overlaps the Wild Cat's lower range. However, budget wise I think the dollar value for the planking and framing material for the Wild Cat would be a fair bit more expensive if a material cost comparison was worked out. For me I think the limiting factor is that my garage is only 20 feet long, so I would build the Aqua Cat as it would fit inside. If my garage was bigger I would rather go with a Wild Cat.

Have fun with your build.

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