Clinker boat design

[kengrome]

Sure Ken, but this is not a lapstrake boat.

You got me there, I guess I wasn't very careful when I made my previous post. I was thinking about the type of construction that uses flush panels and that's not lapstrake, is it? What is it, carvel? Or clinker? Sometimes I don't distinguish one from the other (like this time) and obviously I should be more careful about this. Sorry about that.

One of the reasons for beveling the strakes is to make them look thinner. thicker can make a small boat look clunky.

I can understand this, but traditionally the strakes were something like 25 mm (one inch) thick even in the smallest boats, weren't they? So if I use 4mm strakes I think I should do something to make them look a little bit thicker, especially if I'm going for the wider laps in an effort to turn the waves downward and reduce spray -- and to have enough of a shadow beneath each lap that the boat actually looks like a lapstrake boat rather than carvel planked boat.

If a boat has no need for frames for strength, I see no reason to ever include them in its construction. I almost never use frames.

Same here, but I use bulkheads to create flotation compartments, seat backrests, footrests, anchor wells, etc. and usually these transverse vertical (or nearly vertical) panels do dual purpose as molds on the strongback and also in their final role as part of the finished boat.

Actually the only 'frames' I've used in a long time were in the Tolman Seabright I built, and I only used them there because the plans call for them. If I had skipped them I would have been better off because now I intend to install longitudinal box seats on either side of the boat, and these built-in seats are going to provide far more strength than the frames I originally installed. They aren't full frames anyways, they go from the wales to the bottom only, so I guess they should be called 'half-frames'.

I prefer monocoque construction for lightness and include seats, air tanks, gunwhales, etc for stiffness.

Yes, you're describing the same way I use these components. I much prefer monocoque construction since it generally results in a much stiffer and stronger boat -- and often lighter and easier to build too.

The thickness of the laps should have some relation to the size of the boat since the eye expects to see thicker planking on larger boats.

Agreed!

In the Pop Gun inspired boat in my previous post I used the same number of strakes that the original designer used -- 4 per side -- this on an almost 16 foot long hull. Here's the original so you can see what I started with. It's the top three strakes that are most visible, the bottom strake (or garboard) tends to disappear somewhat due to its angle and position on the hull which puts it mostly under water:

http://dngoodchild.com/5367.htm






Weston Farmer designed this boat as a dory and I don't like the flat bottom for my purposes so I gave it a shallow vee bottom -- enough to eliminate any pounding but not so much that the boat becomes inefficient or unstable. I also made my bottom a bit wider so my sides don't have as much angle to them as the original.

It should be a nice little 'slow and seaworthy' fishing boat when I'm done with it ...

[kengrome]

I gave it some thought and decided that this particular boat is a good candidate for a relatively simple tunnel-stern hull. It's a slow boat to begin with so it may move faster under the same power with a tunnel stern (which thrusts the water at a downward angle thus counteracting the natural tendency of planing boats to squat) ... but the main reason for this modification is shallow draft and propeller protection:

I motor over shallow tidal flats in this area, and sometimes the tides are so low that it becomes a very long wait until the water is deep enough at the beach to launch or retrieve the boat. With a hull that allows the propeller to require less depth my launch and retrieval times are expanded. Not only that, but with the prop tucked up into the hull as shown here it will be less likely for me to hit something and damage the prop.

I lowered the garboard panels almost 6 inches aft. It's important to insure that the aft chines are well below the waterline in this type of hull so it won't suck air into the tunnel and cause the prop to ventilate. The front half of the hull is still the same as before, with the same shallow vee retained to cut through a chop with no pounding.

I think this might be a nice little boat for folks who want extreme shallow draft while motoring at a relaxing speed. There aren't many people using small inboards these days, but modern boats like these could encourage more people to consider them.

[tom28571]

It's an interesting looking boat Ken. Weston Farmer is probably my favorite designer from the old school. Highly practical boats that also look good. Are you going to build this boat? Will it have one of those cheap Chinese engines you talked about earlier? Have you worked out the hydrostatics? I guess we have not hijacked this thread too far since it is still a lapstrake boat.

By the way, my friend, who is re-doing the lapstrake boat that I built for CNC cutting is doing it with no bevels on the laps. This will make the planking appear thicker and he is filling the gap at the laps with epoxy and filler. That is easier but sometimes I just take the long road.