Displacement Hull Power Catermaran

[willy13]

One must wonder what happened to this plan.

I stayed away from it. But one thing bothered me. If you take a used 23’ planing cat and 8’ wide trailer version and put slow engines on it; that boat is only sea capable at say 110% of beam or 9’ seas. Without being able to get over the hump and go to port; it changes the operating paradigm by quite a bit. Even power at surf, etc. is a question. And then weather helm. If you power just enough to run at displacement; then encounter a 20 kt headwind; the boat would need some excess of power to not blow sideways. This gets into all sorts of issues not discussed here. The prop sizing for 15hp outboard would be limited by the plate and most likely props would be undersized for any weather except downwind.

It was not my original plan to convert a planing cat to a displacement cat with small outboards, it was suggested by a forum member. I was simply asking questions about displacement cat hulls and what would happen if they were pushed beyond hull speed.

I am currently converting a 23ft San Juan sailboat to a trawler and getting experience working with epoxy/plywood. I must say that I am warming up to epoxy/ply construction even though it is not as environmental as aluminum construction.

My future plan is to convert an inexpensive sailing catamaran that needs rigging to a power catamaran. First I need to see how much my wife and I like to live on the ocean.

 

[WarrenM]

Hi , glad to hear you are starting with a rebuild. The San Jaun 23 is quite small so your wife might have difficulties with it unless she enjoys camping. I would suggest you look at the Richard woods designs .
They are designed to be built from sheet goods , plywood but would easily convert to sheet aluminum , they may have aluminum plans available.
here is a you tube channel of sombody that did built a woods design , they used fiberglass but the design works well

 

[willy13]

I very much like Richard Woods designs for power cats and have followed some of Fallguys build. I think there might be someone who I can pay to build one of his hulls, but I haven't pursued it yet since I am going to use the San Juan to test the waters.

 

[WarrenM]

I very much like Richard Woods designs for power cats and have followed some of Fallguys build. I think there might be someone who I can pay to build one of his hulls, but I haven't pursued it yet since I am going to use the San Juan to test the waters.

Good plan!