For my coursework I need information on small dinghies.?

Question

I need as much information as possible on heeling and the angle that a boat can heel at before capsizing. I haven't been able to find any good books detailing this so if you could point me in the direction of any that would be great. Is there a heeling angle that makes you sail faster? Or is the boat fastest when flat?

Answer 1

As usual, it depends...

Every boat is different.  Displacement hulls (like on keelboats) are different from planing hulls (like on power boats) and have a theoretical top speed that is proportional to their waterline length.

Dinghies are usually designed more like planing hulls; they have flatter bottoms and can ride up out of the water and go faster than a displacement hull of similar length.  

When a displacement sailboat heels, more of the hull surface is in contact with the water, which artificially lengthens the waterline, increasing the possible top speed.  The extent to which this occurs is determined by hull shape.  This does NOT ensure that the boat will be sailing faster; it simply increases the upper limit placed on that particular hull by its design.

When a dinghy heels, the wide flat surface loses contact with the water, resulting in less friction from the water, resulting in an actual speed increase.

However, in all cases, when the boat heels, the sails become less efficient, as wind spills out of them.

So, heeling WILL increase the upper speed limit for larger semi-displacement hulls and MAY increase actual speed, but it would only be practical in higher winds when the boat would already be travelling at its theoretical maximum speed anyway.  The optimum heeling angle would be different from boat to boat due to hull shape.

Both types will be faster when heeling, but if you are already at planing speed in a dinghy (you should be hearing a humming sound from the hull or taut lines), heeling won't gain you much more speed.

Answer 2

Try searching for books by the great dinghy designers of the 1950 to 1970 era (Uffa Fox, Jack Holt, Poul Elvstrom, Morgan Giles, Austin Farrar, and others). Some of those guys were engineers, knew their stuff, wrote detailed technical explanations.

Southampton University has a marine design course, must have good books in the library.

Dinghies move fastest when sailed upright; but when the wind is very light, when you heel the boat to make the sails fall into shape, sacrificing best wetted area to get good air flow in the sails.

Answer 3

Sailing dinkies are very tender so wind heel them over quick so you have to be on the ball as to not have them heel to far & capsize> All sail boats heel some more than others> Speed is up to the captain knowing the hull he is sailing> Heeling to far to spill the air does not make you go faster only unconfertable>

Answer 4

A sailing boat will be fastest when on a even keel, that is upright, however it is usually impossible to keep them so when sailing. As for capsizing it is possible for someone who is fast to have a dinghy flattened and to step out onto the keel and right it before it capsizes, however most will be considered capsized at 90 degrees.