Headsail Leach Flutter

[msponer]

The boat is a custom design, a flushdeck pilothouse cutter with a lift keel/bulb. Her waterline and displacement are very similar to a Van De Stadt Samoa, though she has a shorter masthead rig with a lower SA/D (16 instead of 22) and slightly less beam. To my untrained eye, they look about the same underwater. We have a feathering Autoprop, but the aperture in the swim platform for the transom hung rudder looks like a source of drag:

Video of a glorious reach with the rudder aperture dragging

Partly with that drag in mind I've removed the genset, a/c, dive compressor, and a few other things in back to try and lighten her stern. Next is moving the batteries forward, though there are other priorities right now (including playing with the kids).

The sails work wonderfully in lighter winds (~15 knots), and in stronger winds if we crack off about 10-20 degrees. There's no flutter and we easily go 'fast' compared to my previous boat, so I'm happy on other points of sail. But I want to figure this out, since we got this kind of boat to feel like we can do what we want: to follow our idea of fun, wherever that evolves to. So being able to beat well is important in keeping our options wide open.

I'll try sheeting the staysail inboard of the shrouds.

Thanks again.

[estarzinger]

Originally Posted by msponer

The boat is a custom design, a flushdeck pilothouse cutter with a lift keel/bulb. Her waterline and displacement are very similar to a Van De Stadt Samoa . . . they look about the same underwater.

I can tell you the Samoa is a speed boat upwind. So, the good news is there is probably some significant improvement opportunity for you.

I might not have been reefed in those conditions . . . I would have in 'cruising mode' (when we reef at about 20kts), but with the cat ketch behind me I probably would not have been Hawk sails fastest (upwind) at 25 degrees of heel, which is quite a bit and we usually only cruise at 15 degrees.

Weight does matter, even on these heavy true cruising boats. Hawk has much different performance, very noticeable, with empty vs full tanks.

[eyschulman]

You and many of the others on this site are not going to like my post its to close to the naked truth. #1 roller furling sails often are pigs in windward sailing conditions particularly in a fair blow. #2 From the videos your sail trim and the passing boat says volumes, you probably don't know very much about sail and boat trim and I strongly doubt you spent much time as a successful racing skipper. A very well know sailing authority once stated he has met many cross oceanic sailors who really don't know how to sail (two different skills) And I also believe that. You can continue to sail the seas as you are no problem. But if you want to know why and how to, My advise do some reading about sail and boat trim and apply it with personal experience racing one design.

[Jim Cate]

Well, it sounds to me like you have eliminated many of the possible causes for slow upwind sailing... leaving blown out sails as a probable culprit.

If you lack the knowledge yourself, see if you can get a sailmaker to come for a quick sail with you. It will not take very long for him to analyze your sail shape and make suggestions (probably with the result of his bank balance increasing whilst yours decreases). Parasitic drag from things like your notch are not good, but don't add enough drag to cause such dramatic performance losses; poor sails surely can.

Cheers,

Jim

[MarkSF]

I haven't sailed a cutter, but my understanding is that the beauty of one is that you can have a large genoa for light winds, and a smaller jib as the staysail. In strong winds you then use the staysail only - and avoid the perennial problem of the genoa losing shape as it is furled.

The ones I see sailing in SF Bay seem to use both foresails in light winds, then the staysail only in stronger ones.

[robert sailor]

In my experience beating with 2 headsails doesn't work very well...the slot is too closed between them....much better off with a single properly sized headsail. If your headsail is partially furled it will kill your pointing ability. With a leech flutter like that your also de powering the sail. Unfortunately most staysails are too small and there is a big gap between the furled headsail and the stay sail on its own. No staysail that I have ever owned or sailed with did very well in 20 knots upwind. Go out one day and sail up wind and slowly bring the boat higher to windward and watch the tell tails on the jib...if the top one breaks first move the fairlead forward, if the bottom one breaks first, move it back. When you furl its a good idea to have the foot of your sail marked and your fairlead position marked so you can move it forward to the correct position. Make sure your leech line is tight enough to stop any flutter after the car is positioned correctly. Also make sure that you have the correct halyard tension so your draft doesn't get too far aft. If your sail has a deep hook in the leech after the minimum adjustment to stop flutter then it needs to be worked on by your sail maker. looks like you have had some great trips..having the kids along is very cool.