Water Ballast

[goolawah]

Hi all,

I'm new to this site and not sure if this is the correct forum for my question, but I'm starting here because it's about wooden boats and that's my thing. Have just competed restoration of a 35 year old Mirror 16 sailing dinghy preceded by a Mirror 10, preceded by a 21' 6" Robert Tucker Ballerina 2 (abandoned project).

Having come to the conclusion that the cost and effort outweighs the rewards I have decided NOT to restore any more old plywood boats. The next project will be a new one from scratch.

I am kicking around with designs and will probably end-up designing my own (will I never learn?). This will probably be a 16 to 20 foot trailerable pocket cruiser of some sort. I'm not interested in racing speed but would like a roomy cabin and stability.

It seems that the idea of water ballast has been used successfully by some designers to provide stability on the water and lightness on the trailer. I would be interested to hear of other folks actual experience with using water ballast.

[Tactic]

A 16 - 20 foot trailer yacht will not be very heavy.Mine (20 foot) is less than 500kg ( plus trailer).I wouldn't bother with water ballast on a small boat like this.
Any modern 2 litre car will launch ,retrieve and tow a boat like this just fine.
Good luck with the design,I am kicking around drawings for a 23 foot cruiser racer.

[goolawah]

Thanks Tactic,

Yes, I know what you mean. Our Mirror 16 has a hull design weight of only 260 lbs and tows easily behind our Camry. However, the 19' 6" bilge keeler I built 40 years ago, and the 12' 6" Robert Tucker Ballerina I started restoring a few years ago, both had 400-500lbs of lead ballast which gave great stability. But they were designed to live on a mooring. I am wondering if some water ballast would provide some of the same stability (in addition to centreboard) when sailing but not add to the weight when towing.

[goolawah]

By the way Tactic, can I ask what hull design software, (if any) you are using?

[Tactic]

I use "hull form" to design the hull shapes..then Autocad to draw up the details etc.
Nothing fancy

[PAR]

Water ballast is a fad when used in small craft. It follows racing yacht trends, like most everything and isn't a great idea in the first place. The current trend toward canting keels, twin rudders and other devices unique to high dollar racing efforts are now trickling down to the designs on production boats, interested in capturing some of the new glory.

As has been pointed out, you don't need it in a craft of that size, unless you are towing with peddle power. Even a ballasted fin keeler with 50% of it's mass in lead will be reasonably easy to drag along, because rolling weight isn't that difficult to move and the displacement of a fat, well burdened craft, in this size range wouldn't amount to much over a ton.

It truly depends on what you need in this design. You've mentioned a centerboard, suggesting a shoal boat, which lends well to the light weight vessel and is easy towed. Shallow draft limits hull shape and accommodations, so a deep bellied, heavier displacement form is less likely. If you have the experience and skills necessary, draw up some preliminary sketches and work out the displacement. You'll find it's pretty easy to have a good hull form and reasonable towing weight. Leave the fancy engineering/marketing ploys to the advertising departments of the major manufactures. Simple is usually much better then over working, thinking or designing things, in the long run. Cheaper too . . .

[LP]

Goolawah,

I was delving in to this arena a while back. Look at the "25' trailer sailer" thread under sailboats. Good luck.