Minuet Yachts: a 2m fun boat-can the design be improved?

"Man who say it can't be done shouldn't interrupt the man who is doing it."-- Confucius

 

+1 to the J6 response

The limitations of the cardboard construction were pretty obvious.

But the "throw it together and try it out attitude" seemed to allow for a pretty good test sail.

If you want to duplicate the original profile in something more durable, a strip build would be a pretty quick. I would recommend 1/4" (glass both sides) or 3/8" thick (glass one side, but good waterproof on the other).

You seem to like cheap. If have the an electric hand plane, you may be able to scrounge some decent wood off of pallets and then thin the material down.

If you do the strip build, I would recommend that you focus on getting a good smooth sealed inside surface first. Build temporary frames for the outside, and hot glue the strips to the frames. With all the strips assembled, glass / or seal the inner surface. Add any permanent inside frames next. Then remove the temporary stuff on the outside and finish the outside.

 

Yes, I've become acutely aware of the limitations and necessity of sealing it up well. I've made a boat with partial cardboard before, and that one has lasted 4 years so far with no signs whatsoever of any problems. I won't be disposing of the pocket yacht any time soon, I'm simply rebuilding the bottom in fiberglass and glassing the inside of the boat as well. The inside wasn't even glassed, just varnished. That was not adequate, especially in the bottom of my seat where the water tends to pool. All things considered, I'm pretty happy with the way things went, even though my boat is temporarily out of service.

If I build any more, they will be skin-on-frame. I really like SOF and the only issue here is a lack of swamped buoyancy with a 50 lb keel, so it would need airbags or foam.

 

Nobody said it couldn't be done - clearly it can but the state of the structure after the first sail should give some serious pause for thought.

The advice I gave was that it would not be sensible to go too far from shore in such a craft. The OP has 50 lb of lead tipped keel presumably sitting between his legs and given the state of the bottom of the boat after the first sail it seems entirely possible that an unexpected structural failure would potentially leave the sailor tangled up with a 50 lb lead sinker attached to their legs.

The OP's safety appears to be genuinely at risk here. It is time to think seriously about the safety implications of the original and revised construction approaches to ensure that any shortcomings do not result in a life threatening situation.

 

It's his to risk.

I applaud him. My comments about Confucius and you stand.

 

We'll have to re-evaluate after reconstruction. I agree though, I need to make contingency plans for the 50 lb lead keel. I may stick some sort of backup flotation around the hull of some sort... Maybe milk jugs, maybe something else. I could go with expanding foam, I'll have to see. The outside of the boat had no issues, it was the inside that had the problems. I am convinced that you need to fiberglass both the inside and outside.

 

As far as glass on both side of cardboard, have you thought about small defects.

Any pinhole leads to water soaking in that tends to just accumulate and only very slowly dry back out.

On wood, it is something to watch for and take care of before rot.

With cardboard, all strength goes away pretty quick with a little water.

 

Yes, this is a bit of a trial run. I haven't run into any pinhole situations that I know of. I guess you just have to trust the epoxy and paint layer. They sure seem thick enough and when I look it over it is one continuous solid layer. Like I said, this was an interesting trial, but I would not recommend this construction method to anyone else. The only advantage is rapid construction of the general shape at basically zero cost. It might be perfect for making molds, but I would go with skin on frame personally. I have had much success with that, and the products are very light and still stand up to punishment.

 

Even if it is perfect when you make it, dings and abrasions during handling can cause cracks in the epoxy leading to the leaks.

 

What about the paint layer, assuming the damage leaves a scratch through the paint, then the paint would be rendered useless for waterproofing? So basically the only way to get around it is to make the fiberglass layer quite thick, is that correct? How come I never see production fiberglass boats leaking through the glass hulls if they get cracks in the epoxy?

Currently it only has one layer of 6 oz glass cloth and 3 coats of epoxy, with 2 coats of paint(below waterline) and spar urethane(above waterline) After rebuilt, the belly would have several layers of glass, probably mat fiberglass. I'm not sure how many layers to do though.

 

I finally put together the video of it's maiden voyage.

https://www.youtube.com/watch?v=LtAlfZ78764

 

Congratulations,again!

 

Thanks Doug! What do you think about the handling?

 

I can't tell much about the handling from that video. Seems like she went upwind ok. I couldn't tell how well she tacked. I think you should be proud of yourself!
There's plenty of room for improvement with the rig, the finish and materials but you know that. You might want to consider that a lot of times boats are judged by their level of finish-it doesn't matter on a prototype but as you improve the boat consider improving the finish unless it would add too much weight.
How did you first realize you had a problem with the cardboard-when you got back in or as you were sailing?

 

I first realized I had a problem when I was packing up the boat and putting it on the car after to take it home.