Join Date: Jan 2012
Location: British Columbia
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Re: Bob Perry's take on Wolfenzee's dream boat
The probelm is the sliding hatch, impossible to seal completely. I gave that up almost 40 years ago. If you give the back of your cabin about a 25 degree slope, it puts the top of the opening as far ahead of the bottom, as a sliding hatch would give you with a vertical back. Thus, with a single door and no sliding hatch, it can be just as easy to walk thru, as a boat with a sliding hatch and a vertical back on the cabin would be, and a lot easier to make airtight. Your feet go down before your head reaches the front of the opening. The slope also makes the cockpit a lot more comfortable for lounging in. As any pressure would simply force the door inwards against it's seal, you dont need all the dogs a coastguard boat has, just a simple one dog. I put the handle at 90 degrees to the dog, so if it slams, the dog will stop it from slamming the fingers, altho using aliminium for the door, it feels almost as light as a piece of cardboard, as long as you are not so foolish as to put a lot of heavy, decorative woodwork on it , to make it super heavy.
Laid back against a 25 degree slope, it is unlikely to slam by itself anyway.
For a forehatch, I notch the corners out of a piece of 1/8th aluminium, have the four sides bent up in a brake press, along with a couple of diagonal kinks for stiffness, and weld them. I give this cover 1 inch of clearance all around the hatch coaming, then cut the sides to fit and just meet the cabintop as the coaming meets the top of the cover. Then, one gasket outside on the cabin top and one inside on the hatch top and you have something very water and airtight. Both gaskets would have to fail simultaneuosly. If the outside leaks, the water would have to fill the one inch clearance completely before it could reach the second gasket. This hatch can be made out of scrap aluminium for under $25 and is a far better hatch than commercialy made ones costing hundreds of dollars
Brent Swain, Boat designer, Builder, and author of "Origami Metal Boatbuilding"