Exceeding the hull speed on older longboards

[swchandler]

My first board was an F2 Strato that I bought in 1985. At 11'10" it was considered a longboard, but not quite a full raceboard like F2's Lightning. However, they shared a planing designed hull with footstraps, an adjustable mast track, and a daggerboard. My board was certainly nothing like the original Windsurfer, and if you looked at the profile of the deck and bottom shapes, it was totally obvious. The Windsurfer had a rounded bottom from front to back and side to side. The F2 on the other hand, was more like modern short boards where the rails turn down from just behind the mast track and form a crisp edge for good water release. Once up to planing speed and in the straps, only the bottom of the board from the straps to the tail was in the water. Just like a modern shortboard.

Although my F2 would guide pretty well in sub-planing conditions, it certainly was no match for full on displacement hulls, or even the original Windsurfer. Again, the more rounded bottom shape was the key to superior sub-planing speed and glide, but these designs just can't compete with the planing designs once the wind builds to allow planing speeds. The rounded bottom shape and rockerline just doesn't unwet and allow the front of the board to rise above the water and overcome its wake in the same fashion as planing designs.

[whitevan01]

biologists!

All science is physics - the rest is stamp collecting Ernest Rutherford

[joethewindsufa]

yeah, butt all this talk about round bottoms has me all excited

[konajoe]

Hi Ittiandro!

I'm not sure how I'm coming across, but I'm really trying to help you.

I know you really want to trust your source, but the best thing that you can do for yourself is to forget about that equation completely. It's a general equation for keel boats that are not capable of planing. ALL reasonable designed sailboards are capable of planing. Their waterline changes with speed and point of sail. Even what we are calling displacement boards plane. http://www.opendivision2.org/?attachment_id=246#main

The light wind performance that you are looking for usually comes with increased volume, reduced width, and increased centerboard size.

The double concave/ concave/ vee stuff is very, very subtle, and won't have any effect on light wind performance.

Sail size, tuning, and design DOES have a big effect on light wind performance.

Vertical rails have a big effect on light wind performance. Boxy, parallel rails make a hull track very straight and true. They go straight, but are hard to turn. It really gives a good glide sensation. Boards with round rails, like the original windsurfer and Kona are more difficult to keep going straight. The glide is not great, but they turn quickly.

Any help?

[konajoe]

A VERY deep vee in the bow, as in the board in the picture in my last post, and the original Mistral Superlight, will give a good light wind glide without boxy rails. Again, this is due to the directional stability you get when the bow is in the water in light wind.

Big fins will also make a board more directionally stable and give a good glide sensation.

So, high volume, narrow, big centerboard, big fin, boxy rails OR "displacement" bow gives good light wind glide.

Equipe II: check, check, check, check, check. (Just give yourself alot of room when you want to turn around.)

Bic 293: Big fin. That's it.

[isobars]

"An Equipe is a displacement hull, not designed for planing?"
I owned the first one in the mainland USA. Rode it from 1984 into the early '90s. It was mere transportation when not planing, a lively and very fast and spirited board when planing, compared to the other LONGBOARDS (screw its length; it had a daggerboard) I had owned or ridden.

All this redefinition of the term "longboard" sounds like Bill Clinton's lame attempts to redefine "sex" -- which he "did not have with that woman" 50-some times in the oval office -- as including only conventional intercourse. Some kid came on here a few years ago and tried to claim that sex has been redefined now; Good luck with that. I guess he thought BJs were invented in college in the year 2010, rather than by Eve.

Yeah ... THAT Eve.

Sorry, dude, but if it leads to orgasm, it's sex.

And if it has a real daggerboard, it's a longboard. Bic may have blurred the distinction by putting some kind of centerboard into a stubby board, but oral sex is still oral SEX, IMO the term "longboard" still normally refers to hardware rather than keel length (I've owned a 10-foot shortboard), and once any board I own reaches the water it gets the crap sailed and crashed out of it; what good's a toy if it can't be ridden hard and put away wet? I haven't damaged a board in >20 years (not counting substandard finbox installations) since I figured out how to pad them unobtrusively.

[adywind]

Which would be faster in displacement mode : sailing the longboard with its dagger out and keeping it flat or sailing it with the dagger in and weighing the windward rail instead to point /in very light wind before the dagger would be able to start lifting/ ?

[whitevan01]

ady,
Dagger down and heel to leeward, not to windward, like a sailboat. The dagger always provides lift, that's its purpose, again like a sailboat. Heeling the board to leeward will cause the board to turn towards the wind and increases the effective waterline length, which causes the distance between the bow and stern waves to increase, thereby increasing speed through the water.

In addition, your weight should be positioned a bit forward so that the stern (tail) of the board is not dragging. the board should be level fore to aft.

Weighting the windward rail of a board with a daggerboard down will cause it to turn downwind, not upwind. When the daggerboard is down, you must weight the opposite rail to get it to turn in a certain direction. So, to turn to windward, weight the leeward rail, to turn to leeward, weight the windward rail. Having said all that, one must use the sail to turn the board also.

[adywind]

[techno900]

Using the proper technique, it's ALWAYS faster upwind with the dagger board down in any wind (1-30 knots). Over 20 knots, one may have to kick the dagger up a bit to keep the board from "turtling" (too much dagger lift).

Proper technique means leeward rail down, windward rail up. That's why most racing longboards have "hiking" straps. Usually, only one foot is in the strap, with the other foot placed as needed (sink the leeward rail in light winds or hold down the windward rail in stronger winds).

Even on a beam reach, you want to convert the lateral wind forces into forward momentum, and a dagger helps. As speed increases, the dagger is moved up and should be all the way up if planing with good speed (in the rear straps).

I have raced a windsup with a dagger and it is very efficient in light winds, but needs the dagger board down to make any real upwind progress.