Robb White's venturi dagger board Trunk?

[jrassier]

While I was reading Robb's  " How to build a tin canoe"  he described  a long streak of aerated water visible astern of the dingy he was towing.The dagger board slot of his design developed a venturi effect that pulled air down the slot.  Anyone out there with knowledge on the construction details of this stroke of genius ?  I'm shaping my dagger board for a  Spindrift 12. Next step will be the nerve wracking hole for the DB trunk

Jim

[Hirilonde]

The angle of the daggerboard trunk and the size and shape of the daggerboard on any well designed boat is part of the total contributions that equals a balanced rig.  I would built it just as in the plans.  Hmm, as a matter of fact, I did build my Spindrift 9's as designed.  What ever was done in that boat you describe if much different at all than the plans might make for this nice foam in the wake, but will very likely have a poor effect on sailing.  Most people who tow sailing dinghies make a false daggerboard to go in the slot and fill it for towing.

[Greg Luckett]

...I'm shaping my dagger board for a  Spindrift 12. Next step will be the nerve wracking hole for the DB trunk

Jim

Any pictures to share?

[PAR]

No stroke of genius, a common issue on sailing tenders under tow. It also happens if you're powering. If you install a case cap that is well fitting, you'll stop sucking air down the case and creating turbulence under the boat. Now there can be advantages to this sort of thing, but you need thousands of holes to bleed out air while under way. I made a pin cushion of a planning dinghy's bottom, many years ago in an effort to try this. The effect was barely noticeable and keeping thousands of holes clean and clear was problematic at best. I've also oozed oil and soap out of holes and few other novel tricks to entertain myself as a youth.