Bow Wing

Re: adding to pitch-pole problem, if you refer back to the original photo of Bruce Schwab's boat, at http://www.bruceschwab.com/updt_usa05_2004/news_071904.html
you see that the underside of the wing is at a sharp angle to the hull, but the top side of the wing is at a very low angle to the bow. I believe this would mean the wing would be very effective at hitting the water below it, but would have little effect if hitting water above it.

Andy Evans
Foolish Muse.

 

Everyone is right to some degree.

OP should have had more bow flare (a la Moore 24...sorta) and a bit more freeboard up front. I actually pushed for more and this is one argument I wish I had won. The boat did not "pitchpole", it was a matter of too much water on the foreward foredeck really slowing the boat down when zooming into wave troughs. To change the hull and/or freeboard was not an economical option, so we looked at everything from the "Grundig" wing to adding foam/flare. The wings we figured would break/be too much drag/and possibly make things worse as mentioned above. Adding flare with foam would be too much material and heavy.

In the end, the combo of dynamic lift, low drag, and low weight from our version of a "bowlip" seemed worth a try. I'm happy to say that it really does work. Sure, water/spray stills goes on the boat, that is unavoidable, but the heavy green water on the nose is pretty much prevented and the boat no longer "stumbles" when nailing the back of a wave. Also, when working on the nose to hook up a genniker or spin tack I don't slammed like I did before.

So, yes it is help and we are leaving it on there, but the question for Andy is it really rough enough on the way to Hawaii to require it. In my experience it could be in a windy year or in big squalls, but on the average, not really.

Haji

 

Hey Bruce, you a permanent easterner nowadays?

Yoke.

 

Are we talking about a wave 1' higher than the bow or a REAL 10 to 15' one. That scrawney little fin should do nothing when a wave 5' higher rolls over it. Look at the area of Penguin or Tuna flippers to body size. I think we are day dreaming on this topic. Race cars NEVER drop their front to a negitive angle, ever.

 

Well, it should do something. What are we talking about - say 4 square foot wing area (say 0.4m2), 20 knots (say 10m/s) Cl = 0.5 (rather uncertain since it may well ventilate) then that is about a ton of lift. OK, it may well be quite a lot less than the bouyancy lift due to the bows being deeply immersed or submerged. Probably most worthwhile for a boat with narrow bows, eg a typical multihull.

John

 

Not according to Sean, and he should know. He says they were there for lift but IRC wanted to look at the rating with them.

 

Langmans bow wings

Mr. Langman also said they worked very well downwind but because they were not retractable they weren't so hot upwind.

 

One time I had a Hobie twelve, yes twelve, foisted off on me. It would go pretty well but had a nasty tendency to bury the lee bow in a breeze. The little boat was too much fun to abandon. On the other hand I had no desire to be pitchpoled which was a sure thing if pressed on a breezy reach.

I had an old daggerboard that was nicely shaped. With a little surgery it fit between the bows. It was installed, horizontally of course, a few inches above the water surface and given a healthy incidence angle. Problem solved. When the lee bow went down, the board, now a wing, would lift enough to offset the problem. Spray a plenty, but it worked quite well.

All that said, I fear you might get into some structural problems on a monohull of the size you mention. A failure of one side of the wing could make a serious problem. Too serious to fool with.