Slow port tack speed

[bgruen]

For the last few weeks we have seen the performance of our boat drop considerably. In light wind where we would normally leave all the bigger & heavier behind, we are now struggling to keep even with them. This weekend we started a race on a starboard tack and held 6.3 to 6.5 kts for 2 miles to the first mark, pretty much leading the fleet. Then the others started passing an we slowly fell behind.

When switching to a port tack, our speed was 1.25 - 2 kts slower then on starboard. We noted this all afternoon in all weather conditions. Always slower on the port. We were also unable to get anywhere near 6 kts the rest of the day. ( yes I checked for dragging anchors )

I have the shrouds set at 23 & 25 , plenty of rake,,,,, We tried several drivers, but none could break the slow boat cycle..

Sails are in good condition and have good shape. Bottom was scrubbed a couple of weeks ago. Lake Michigan cold water..

Any ideas ?

[Mark Gutteridge]

Just spitballing here. Headstay length changed,water in boat, keel damage, keel not seating properly?Good luck!

[bgruen]

The board was good last spring, Haven't seen it since, I'm not sure how it is alligned etc, in the trunk when it is down.. ( not sure what to check or what to look for ) ..

[dave]

Check the leading edge (at the center seam) of the board for delamination. I had the same problem the last season that I raced 298. We were always .5 knots slower on port. Part had to do with the fact that the board trunk was glassed into the boat crooked and part was that the starboard side of the leading edge would open like a jet scoop when on port tack because then, that side of the board was in a low pressure area. On starboard it was under high pressure and apparently stayed close.

I cut to small sections of batten and epoxied one to the forward/starboard /inside edge of the board trunk and did the same to the aft/port/inside edge. This got the board closer to CL when fully down. As a VERY quick but non permanent fix I Superglued the delaminated skin/edge down and then taped it while the glue cured. Instant identical speeds on both tacks!!!

Just as a side note: your knotmeter sounds a little high. Hull speed on a 21.75' WL is just under 6.25 knots and small/heavy keelboats with high freeboard and relatively fat masts make lots of drag when sailing upwind............................... which means that you won't hit hull speed when sailing that direction unless many things take place at once like flat water, 7 people hiking HARD and the perfect wind speed. Even then I don't think you can ever make hull speed upwind on a 7.9. The last season that I raced 298 our knotmeter was darn close on calibration and when we were hauling the mail and really cleaning the rest of the fleet's clocks we were seeing something in the 5.5 knot range.

It's all relative from one tack to the other but it's nice to know your TRUE speed so that you have a fast indicator of your performance relative to what the hull is capable of doing. I'd be checking the speed with a GPS for the best results..................... if it matters to you.

[bgruen]

OK, we finally came to the conclusion that it is the board. We were getting walked all over by the big slow boats last Tuesday, until we raised the board ( with some difficulty ) half way, then we got our speed back. The board & boat will come out for the season next week, as the boat also need some repairs from a t-bone we got a few weeks ago..

[Tac Boston]

With regards to the board not sitting right. We always drop the last 6-12" pretty firmly so that it sits right.

[dave]

Tac, I was talking about the board trunk being glassed into the hull at an angle to the center line. If the trunk is that way the board will be too. I haven't had the chance to look at too many 7.9 bottoms (CLOSELY) out of the water, maybe 5 or so. Of those maybe 2 had a fairly centered trunk and the rest were crooked, with mine being the worst that I've personally seen.