I'm new to this forum and don't know how to send PMs, maybe you could share your info here?
I am sure the info could be interesting for other people too.
This is very helpful! I am going to make a drawing based on this to see if I could live with it.
In Norway you need a special certificate to use a boat thats more than 50 ft. So I could maybe change the boat design so that it is just under 50 ft in order to get a bigger house on it.
Maybe 15 meter long and then have a house on it that is 9 meter in length. That could potenitally work.
Is it necessary to have a lot of space behind the house in terms of wind resistance?
Also great that I won't need to have a lot of hp for this to work, it will help reduce costs.
It's not so much the wind I'm afraid of as it is the waves. I wouldn't want them crashing into the house. If they smashed their way in, they could flood the house floor and create a terrible "free surface effect" where all that water sloshes to the low side and causes a capsize.
With some hull behind the house, there is some buoyancy to raise the back of the house up out of the way of the on rushing water.
For the engine hp I said would be adequate, I was assuming a displacement of about six metric tons. This would fit nicely with a 12 m length and a 4 m beam.
Adding 3 m to the length will surely increase the displacement, but the twin 30 hp will give you about 40 to 45 hp of continuous duty.
Going by the lower number, and assuming you will need 5 hp per metric ton, you could go up to an 8 mt displacement.
Everything is going to weigh something. And the weights will add up quickly. The big structural decision will be whether you want the house to be an integral part of the hull structure, or you want it to simply sit on top of it.
There are good arguments for either one. If the house is part of the hull structure, it will look less like a house and may have cross beams you will have to step over. But such a choice will also mean less windage per given wall height, and likely less building cost and weight.
With the house simply built on top, all the cross beams will be beneath the house floor, and there will be space under it to place heavy objects, such as batteries, that you may not want to put in the hulls.
The disadvantages are:
1.) that you would be now building a double structure, the hull, then the house. This will certainly come with added structural weight.
2.) that the floor of your house will be at the shear line or slightly higher. Your walls will go up from there. This will mean more windage, short walls, or maybe both. It will also mean less ultimate stability, as the weight of the house, and everything in it, will be higher up. The side walls of the house can be less than 2 m high, as you need not stand near them, but this will dictate your interior layout to some extent. Sitting and laying areas would be near the side walls. Standing ones would be more near the center.
If the floor plan is to extend to the sides of the boat, a means of getting from one end to the other, through the house, must be provided. I would go with a door at each end that lined up with the other.
I also envision a grated deck at each end of the house, that is at least 1 m wide, that runs from shear to shear. These would provide an at least reasonably quick access to the hull decks on either end of the boat. You will need this access for tying up, casting off, and boarding.
I would go with deep "V" hulls that go about 1 m deep to:
1.) provide lateral resistance (as the house walls produce plenty of sail area), and
2.) produce a slower pitching motion an prevent pounding.
These may have actually less whetted area than hull with a different sectional shape with keels added.
