The Ultimate Sailing-Cruiser?

[FAST FRED]

"A cargo hold type chamber, however, will, invariably, leak at some point and must be maintained AND not leak much to avoid sinking the boat from the inside."

Not if the hatch over the hold is maintained. Amnd certainly not a problem if the hatch compartment is built with water tight bulkheads.

Expensive to put internal water tight doors , so compartment can have other uses, but not much more than $1500 each. OTS

FAST FRED
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[mackid068]

I watched a Discovery Channel show about a cargo ship that sunk simply because the cargo doors, much like those intended for this boat, leaked due to a lack of maintenance. Just keep a regular maitnence schedule and you'll be fine, though there's always a possibility.

[Seafarer24]

Actually, the "Aft Cabin/Cargo Hold" should be an entirely seperate chamber, with solid walls and no bilge. Entrance would be from above, so the people using the sub would step from the deck into the sub and the crew would then lower it into the water. A leak would be a loss of bouyancy, to be sure, but not enough to sink the boat.

[mackid068]

Well, if you do it like that, then it should work. But you've got to keep the compartement small enough that you wouldn't lose too much buoyancy. How about having valves to release excess water or have a bilge pump to pump it out?

[Brasstom]

Some kind of bilge will be necessary, I think. For the sake of argument (cuz MAN you guys hate these underside doors, lol) lets discuss both concepts.

As just ahold with deck acess it may not need a bilge...as long as I have a hatch or door that shuts snugly and will hold out spray, rain, and deckwash...then we're fine, right? I would think mostly...

As a Submarine bay with hull doors a bilge will be essential to the design. Once the doors are tightly sealed the bilge wil have to empty out the water thats will be in from the hull to the waterline. That kind of weight sloshing around, even in only 1/5th of the total hull length, can NOT be helpful for her sailing performance.

with both designs when the sub is out the thing is an excellent cargo bay for extra provisions. I plan to use it to store scuba and other gear even WITH the sub. I have a layout in my head that fits pretty well. But I'll need a model or at the very least a designed layout before I get that far. What I REALLY need to do is know how to design a boat! Anyone have an opinion on Tom MacNaughton's Yacht Design school? (http://www.macnaughtongroup.com/school.htm) I like the price and the ease... I'm wondering if as a college graduate who studied politics and international relations if I can really make this leap to...ya know...math. Advice? Thanks again, all!

[brian eiland]

Originally Posted by Brasstom

What I want is a sailboat with the capabilities of a do-it-all adventure boat. I'd like to build a boat with a length of about 50 ft and a beam of about 15 ft. What would make her unique is that in the center of the hull would be a 10ft by 8 foot bay, like a cargo hold, in which you could put either a very small 1 atmosphere or a decent sized ambient air dive submarine.

I want to hang a very small ultralight seaplane off the back of the boat. The plane's exist and are very light, the greater issue is a stable storage rig for it. Maybe some kind of storage hold in the very front of the boat for a motor-bike or two, should I decide to go larger with the design.
Tom

Tom, why don't you just give in to the catamaran concept. Have a look at this big cat, Star-Tec, with a small seaplane on the rear and other toys. You wouldn't have to go this big for just an ultra light and some lt-weight mini-subs. Sure makes the problem a lot easier....and more stable, and less leakage potential, and more resellable, etc, etc.

Plus the cat is so much more versatile; have a look at this motorsailer discussion.

And you could construct this vessel in a light weight wood/epoxy composite method.

[Plumbtex]

I think that if all you want to do is design one boat for your own use then an education in boat design would be a waste of valuable sailing time. But if you think that you have something to add that would make the sailing/ boating world better and you have the desire to make it a career choice, go for it. When you get old you regret the things you didn't do much more than the things you did. That being said. if you must drop the sub out the bottom, hinge the door at the front and seal the comartment off from top to bottom - access only through the top. Ithink though, that an open transom with provisions to launch / recover you sub via the stern would be more practical, seaworthy and simpler to build. P.S. If you build it and you need a crew member, my bags are packed and my calender is open. Good luck- make it happen!