Its just not fair.

After a lifetime in and out of boats and when I decide it's time to swallow the anchor and look for pastures new you come up with a dinghy competition that would appear to be written for something I did years ago with the grand kids, and which I stupidly get involved with. Then you guys go and (constructively) criticize it and start me thinking boats again. Now you have me criticizing the efforts of the kids myself. It's just not fair.

KISS is not perfect. It is simply the result of a mornings work by the kids, and without any attempt to develop it further. A small change to some of the dimensions could be beneficial.

A small increase in spreader width without increasing the transoms would increase the rocker a little. I might add 20mm here.

A 20mm increase to the height of the side panels along the full length might be beneficial, and only trial and error would show what would be best.

Contrary to what has been said I still think a small increase in the width of all sections would have 3 pros and only one con. The con being only to spoil the attractive ratio of beam to length, but very small boats generally are wide so a small increase should not be too bad. The pros are; increased beam gives increased lateral stability, never a bad thing in a little boat; increased buoyancy for the same immersion so better load carrying ability; and contrary to what David said, I believe the extra width would make rowing easier. The last thing I want on a little boat is my hands overlapping on the pull stroke, particularly when on short trips with lots of manoeuvring. I want to waggle both hands separately. My Seahopper is 4'2” wide and the Avon Redcrests wider and they are lovely to wiggle around an anchorage. I feel that if narrower and the oars would end up shorter and not so powerful. Maybe that's just me, but the kids and Harry's wife Gill love rowing the Redcrest with it's much wider rowlock spacing. On KISS I think I would add 50mm to both transoms and the spreader, plus the 20mm mentioned earlier to the spreader. It's not a lot, but possibly worth doing.

An other mod I would consider involves the bench seat which I feel does not need to be fully ply covered. With the rails fixed a moveable ply seat, wider than the rails could sit aft for one up rowing and be lifted forward for rowing from the two up position. This would use less ply and, covering the daggerboard slot, would leave a dry b--. Of course it would be attached with a short line. With this arrangement the daggerboard case could be set on the inner edge of one of the bench rails.

Graeme mentioned school kids working with epoxy, and I fully agree. I used polyester resin for my first stitch and tape canoe, and all the early Mirror dinghies used polyester resin and they all lasted well. That and cost is why I suggested polyester in the KISS write up.

I reckon (guestimate) the rowing version of KISS would weigh less than 25kg, and while the sailing version would add a few kg, it would take significantly longer to build.

Can I go back to retirement please?

Cheers, Slieve.

⅔ of the width of a sheet of plywood is absolutely fine for the bottom plank, Arne. That's 2ft 8in, or 81cm. That really does result in a very stable dinghy. ⅔ of a sheet for the bottom, and ⅓ for one of the topsides, makes the best use of one sheet, leaving the other topside and the transoms etc to come out of a second sheet. 

Thanks Arne (regarding the numbers.)

David, the trim was not deliberate - its just where I plonked the tub of sand and it looked about right – although if the weight of the single adult were on the rowing bench she would trim a little more down by the bow. But I wouldn’t want to trim KISS down by the bow too much, she just doesn’t have the right shape for that. She doesn’t have the reserve buoyancy up there, forward, that Tender for Siblim appears to have.

I think KISS is a somewhat different horse for a somewhat different course. I might be wrong, but to me the two dinghies are rather different. KISS has a slightly Chinese style, “canard” body – main body aft and amidships, with a protruding bow. Tender for Siblim on the other hand (as far as I can visualise, which is not very far – that’s why I had to make the model) seems to be deeper and more full in the forward sections, she’s “all boat” as they say. Tender for Sibim is a bigger dinghy than KISS.

Talking about altering the design of KISS, rather than just altering the trim of this particular design - in that case David may well be right. In fact I think David is right. In that case, Tender for Siblim is probably the better design to go for, as a utilitarian tender. 

I just don’t have the experience of designing and operating dinghies enough to comment any more so I will leave it there, and hope very much that some other people will continue the dialogue with David. For me, this is a good opportunity to learn.

(Actually, I’d like to make some more models now. There is so much that can be learned from them. But time is always the issue and none of the other designs would be anywhere near as quick and easy as KISS was. And for me, that’s the bottom line).

Arne’s latest post crossed in the mail. Definitely a different horse for a different course, Arne.

Packing 200, 300 – 400 kg into a 8’ tender is getting a bit too extreme for me. I’d rather make two trips. Fat Boy is… well… fat. But a great load-carrier, for sure. And nice and stable too. If it’s a competition to see who can carry the most weight (and still keep the stern clear of the water) I should have entered my scow, with a beam-length ratio equal to that of Fat Boy.

KISS is probably too small for most people – she’s a stern dragger - a pity, but that’s all there is to it. I still think she looks sweet,

More sophisticated (5-plank) but closer to KISS in size and sweetness) is Annie’s little Fantan.

Annie, what are her dimensions? What’s she like?

And in the background you can see Marcus sculling his little wee tender for Freebie – at about 6’ she’s just plain vanilla.

They’re all different, they’re all good.

Nobody has talked much about towability. I would like to provoke some discussion by proposing that most people do it wrong, attaching a tow rope to the outside of the stem. My old mentor Brian Donovan always reckoned the painter should be attached to the inside of the stem and ropes which reside half in and half out of a dinghy are as untidy as leaving oars in their rowlocks - which is also a common habit.

Any half-way decent towing dinghy will sit back and plane even when the tow rope comes from the inside (where it belongs) and is deployed over the stem. I have had just one dingy which wouldn't - it was half a dinghy, actually - unfortunately it was the front half. But that's another story.

No, no. Bad. (Not the boat - the oars and painter I mean).

Good, Arne. But please could you try reducing the beam? The oars should be conveniently stowed inside, and for a 2.4m dinghy, that makes them about 2.1m long. With that length, the beam ought to be around 1.1m, or 3ft 6in, and I've found that to be about right for stability, with a 3-plank tender.

Graeme,
no need to use me as a math professor, your numbers look good.

Arne