Little flattieboat with twin skin sprit sail

[Dieter51]

Sharpie skiff - Chapelle's rules https://www.boatdesign.net/threads/sharpie-skiff-chapelles-rules.29844/

@messabout: This was the thread I stumbled across years ago that prompted me to design an all-wood boat in my old age after all the plywood stuff, which was then built with a friend.

In the meantime I have made friends with the boat, it now runs 6 knots (single-seater) at 3 bf without the "surprises" of the twin-skin-sail and I think it can sail significantly faster sailed - still sitting on the bottom.

There is no pronounced wave pattern behind the stern, that's good. The "new " single sail with the light spars with ball heads is now fun and gives the right feeling.

With the buoyancy aids, the boat now lies higher in the water and popps up immediately when you pull on the daggerboard. Unfortunately, you can no longer stand on the daggerboard to get into the half swamped boat, it immediately tilts to the side you try to - with the water in its belly. Before, the double sail in the water ensured that the boat first remained some seconds on its side, when entering it from rhe dagger board, but unfortunately that is no longer the case.

So now I quickly made a light ladder that always lies at the back of the boat and with which you can get in via the stern. The front yellow tube is partly filled with water, because the boat then sails much better (also heeled) solo over the chop. The 10 kg of water at the front will also help to prevent the bow from standing steeply in the air when you get in at the back with the boat partly flooded. I still have to try that out.

The pump (3,000 gal/h) does a good and fast job on a 14 Ah motorbike battery, after 2 minutes it looked like that. Further 2 minutes, and it is empty. The Paulownia wood shows no weaknesses so far. So I am satisfied.

 

[messabout]

Dieter I appreciate your attention to safety details. I am older than you are and I wonder about my own ability and the boats ability to allow self rescue.

I have never dumped Goldilocks and I have survived some vicious windstorms while still right side up. It is curious that your boat is actually a little wider on the bottom and only about 30 centimeters shorter. Your lovely boat may be a bit lighter than Goldilocks but it is certainly no heavy weight. Less than 60 kg.

You have caused me to think seriously about how I am going to handle a capsize situation. In my younger days I capsized Moths, Lasers, IC 10meter canoes, and came awfully close to flipping my A- cat. I am a lightweight at about 72 kg and was not big enough, even while trapezing, to hold the cat down. As I got older I decided to abandon my hot rod boats in the interest of self preservation.

Sitting on the bottom of the boat does add greatly to its ability to keep the bottom side where you want it to be. I used to sail Goldilocks that way. Eventually I began to trust her and put in some side seats. My weary old bones found the side seats much more comfortable.

I have never used a big sail on this boat. The one I like best is a sprit boomed sail of 5.6 M^2. I sometimes use a Lateen rig from a Sunfish, about 7.4 M^2. Neither of them have been threatening.

 

[clmanges]

Have you considered installing side air boxes? This PDR shows the advantages:

Air Tanks On The Sides https://pdracer.com/emergency-flotation/side-airboxes/

 

[Dieter51]

Hello Messabout, sometimes I wonder how one can be older than me ;-)

Because we made some changes during the construction, such as lengthening the bow of the boat, I measured it: Without the steering gear, the boat is exactly 4.5 m long and the bottom is 1.03 m wide.

The boat weighed just under 40 kg at the beginning, now it is much heavier, around 55 kg. That can't all come from installations like tubes and pump - nor from oiling with a good, water-repellent oil (more expensive than good varnish).

I suspect that the light wood (310 kg/m^3), which is straw-dry dust when sawn and sanded, still absorbs moisture. With the oil and the time in the sun, it has become much harder on the surface. But the boat is still light enough for me on the short steep ramp.

My helplessness after the capsize, when I righted the boat several times and also got into the boat via the dagger board, but couldn't scoop it empty in the wave without more water running in than I got out, warned me. Moreover, I really noticed how exhausting that had become for me at the age of 72.

I think with the tubes now and the small ladder it's a good compromise. If it's slow to capsize, I can go over the windward side onto the dagger board and then quickly back in again, as I used to do with other boats. No problem with the narrow boat. But with the double sail capsizing didn't go slowly, it went "bang" despite the free-running sheet and I was in the water.

The wind is very different here this year. We usually have weak, gusty winds from the east in summer and are happy when we reach 3 BF permanently. This year there is much more westerly wind and often with the warning sign from the weather station that gusts of 6 BF are to be expected at 3 BF. It has been fierce a couple of times, but there were two of us out there.

Now, with better running blocks and the 7 mm sheet from the Laser, I feel safe sitting on the bottom, feet against the leeward wall, even in strong squalls. The boat just has no end stability due to its shape, you have to bear that in mind and should never try to sail alone sitting to leeward. A learning phase.

I wish you continued good health.

Dieter

 

[Dieter51]

Hello clmanges,

I know that the Goose and others were given double sides, which not only greatly improved their mechanical stability, but also made them easier to right and board after capsizing.

The video/photos shows this really well.

But for my narrow boat this is not a solution, because the Boat becomes a bit to small to sail it comfortably sitting on the bottom. We installed the slightly curved thwart last year, so that I could try to sail the boat sitting on that thwart. This is comfortabel, but too much "noseheavy" in good wind. So I decided to use the tubes and later I might install two little decks at the stem and the stern to hide that ugly safety-volume.

Best - Dieter

 

[Dieter51]

Good and bad. Now we had good wind on the lake, 3-4 bft and 6 in the bows.

The good: Paul (the boat) can also be sailed safely from the bottom in these conditions. A moderate 6.2 m^2 sail area with a modest increase in lift thanks to low aspect ratio helps a lot here. The self-made-sail from the "kitchen table" stands well and the spars have the necessary elasticity in the bows, as the mast is very stiff and braced.

The bad thing: Paul (the boat) hammers in some waves that you are afraid the mast might smash through the bottom, which is impossible. You can try to drive the boat on the chine, but in these conditions a stop in the wave immediately brings the water in over the gunwale. It's a knife-edge ride that you eventually lose - and then having the boat swamped in these conditions is no joy.

The speed remained in the displacement range, just under 7 kn maximum, mostly 5.8 to 6. That's not enough to get the boat over the waves well, with any trim attempted. What might help, as always, is a jib. I will try a low-set jib with a low aspect ratio, which is run as a self-tacking club jib. The mast then can be tilted more to the stern without problems.

 

[messabout]

Dieter I have enjoyed our conversations and I do like your boat. I have a strong suspicion that you should seal and paint the boat over the winter season. Oiled wood is fine for classic furniture. Not since the viking boats has water been kept wood from absorbing moisture. In fact moisture in wood causes some woods to swell, which was an essential for caulked seams.

Judging by the pictures, your sailing waters are more angry than the ones I usually encounter. Maybe that is why I have never dumped my little flattie. I have on occasion sailed in some very lumpy water without a lot of difficulty.

Here are a few pictures of the little yellow boat named Goldilocks. Notice the bridge deck which houses the mast. It is not even screwed into place. It has some hidden clamps, similar to the ones used by machinists to hold their work pieces on the surface of a milling machine or saw bed.

Yes, I am older than you are and increasingly cautious about messing about in boats. I usually play in boats at local lakes in my city. There are 21 of them within the city limits. Some of them large enough to get me into trouble on a stormy day.

I have rotated around the sun more than 80 times so far.

 

[Dieter51]

Hello messabout,

I hope that I will reach the number of your rotations, still beeing able to sail. Does not feel so sometimes.

This week I'm in Italy with my wife, no sailing :-(

Our lake ist not that "angry" usually, only if we have a strong westwind. But in the summertime we mostly have wind from the eastside.

Your pictures of goldilocks cannot be opened :-( Red crossed. Just copy them into your text - this worked for me.

If I had to paint paulownia (the wood), it would be a failed trial to build a boat with it. We have an oil here, which is much more expensive than any other stuff one could use to protect wood from rot. I hope, that the wood and the oil will do what they promise. We will se. I guess, the wood "breathes" the water without problems. Hope dies at last ... or so.

Hoping to see goldilocks soon

Best - Dieter

 

[Dieter51]

Waiting for material for new sprits for the new sail, this time from really simple sails (well made!), I started another discussion. See:
Naca Airfoils shape and rocker oft flat bottomed boats (No. 69054)
Perhaps one or the other would like to make a contribution?

 

[Dieter51]

I have a new Sprit sail from Really Simple Sails, Mike Storer. It was reasonably priced, the quality is impeccable and it pulls well!

Now that I've made a few sails myself, I appreciate it when you only have to rig a sail and get one that makes the boat faster and does not change the weatherhelm, which is very light.

Well done, Mr. Storer. A clear recommendation from me for these sails.

 

[Eric Zhu]

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email: zhuwj@sinostsc.com