[Michael Norman]

I have a grp endurance 35 ketch made in 1986. It is fitted with a yankee head sail and stay sail. It sails well except upwind where it seems to make excessive leeway. So much so that beating upwind is a time consuming experience. It also struggles to go through the wind sometimes when tacking when there is a bit of a swell. My theory is that the head sail arrangement is not providing enough drive and l am thinking of changing to a single genoa head sail.

Has anyone else experienced this problem and if so how did you overcome the problem or do did you just live with it as l have for some while.

Thanks

Mick

Topic

[Mark Ayers]

Mick, Does you Endurance have a full or shoal keel, this would be the biggest difference in how she heads to wind, but also I’m not sure what angle of attack you are talking about to apparent wind. Also, how she is loaded is going to effect her performance as well. But when in doubt sheet out the head sails and leave the main sheeted tight. this will use the headsails to make the main more efficient. Also depending on your angle, you may be cutting off the air to your mizzen, so falling off to say 30+ degrees may be much better headway for your boat. Swell, usually doesn’t make that much difference in actual headway, unless your sail shape is off.
Hope this helps… Mark

[Michael Norman]

Thanks for your reply Mark. I assume I have a shoal draft. It is 1.52m, I have seen data for E35s with deeper keels.

Pointing relative to the apparent wind is good. I.e. Looking at the mast head wind indicator she is where she should be. The real give away is the plot on the chart plotter which shows the excessive amount of leeway that is being made. In tacking she is typically going through 140 degrees. I don’t expect a high performance but this makes up wind sailing time consuming. I have tried most permutations of sail tight and slack as you suggest but it makes little difference.

Any chop, not so much swell can stop it going through the wind. I believe that it is lacking upwind drive which is contributing to the leeway and making it problematic in going through the wind.

I am actively considering replacing the existing yankee/staysail arrangement with a genoa hopefully to increase up wind speed. I have discussed this with a sail maker who says he has made a genoa for an E35 ketch before. Unfortunately I don’t know the reasoning behind the change in that particular case other than making sail handling easier.

Unfortunately she is out of the water now for the winter so I can’t experiment any more.

I would welcome any further comments based on this further information.

Thanks

Mick

[Mark Ayers]

Just my thought here, but If going to go to a genoa, I would do 130% or less with your ketch rig.
Also, sail shape is very important. With your 35 you are wanting a power sail shape rather than speed sail shape. The deeper the pocket (assuming it’s in the right place) the more power you get. the more shallow the pocket the more speed, but you loose the power. Your Endurance is probably displacing 19,000+lbs and Hull speed is 7-8 knots I’m guessing. I would make sure your new sail is set for a power draft. That will help move the weight of the boat better through chop and swell
I used to race Hobie 16’s and it taught me a lot about sail shape and tuning.
Best of Luck!

[PaulK]

Lots of variables with the setup you have. Your long keel is not helping with windward performance; such a long foil has a hard time developing lift, to counter leeway. It could also be messing up your tacks if your timing on the swells is off, since such a long keel tends to make want the boat go straight all the time. Are you sailing upwind with the mizzen up too? Your post doesn’t say. Most racers furl the mizzen going upwind because it creates more windage than drive. The sailplan makes it look like the main is well forward, so dropping the mizzen might make tacking trickier – you may have to try it and see. Do you have instruments that show you VMG? It could be that you are pinching the boat too much into the wind for optimal performance. Even though the sails may be full and not luffing, they could be strapped in too tight – like sheets of plywood – and not able to create the lift and drive you need to make good progress. Try easing sheets and heading off perhaps 5º and going faster. You will have to travel farther because you are heading off, but because you are going faster your keel will become more efficient at keeping you from going sideways. If you head up 5º but go sideways 4º, your net gain is only 1º, and you’re going slowly. If you don’t head up 5º but only go sideways 2º, your net gain is 3º, and you’re going faster. It’s a tricky balancing act.

[Michael Norman]

Thanks for your comments I will certainly discuss your points with the sail maker before we proceed. I wasn’t sure I fully understood your first sentence though. I would be grateful if you could expand on that a little.

Thanks

[Michael Norman]

Re psk125 Yes lots of variables. Unfortunately the time for experimentation has passed. She is out of the water for the winter now. I have however tried most of the things you suggest. Mizen up, mizen down, stay sail up, stay sail down, sails in, sails out, sails tight, sails loose. I get a pretty good impression of what is happening across the ground with the track on the chart plotter. The angle of tack stubbornly refuses to improve. The Endurance 35 was never designed as a performance boat and it may well be that this is the way it is.

The real test would be if out there there was another E35 owner with whom I could compare notes.

Thanks for your comments they are much appreciated. At the moment I am planning to change the current yankee/stay sail arrangement for a genoa. I’m hoping this will improve drive and ease sail handling. Fingers crossed.

Mick

[PaulK]

To expand on the difference between long and short keels and lift…

To develop the most lift possible for the wetted surface, naval architects tend to make keels short from front to back. An aeronautical example of this would be a glider. Its wings are long, but narrow. The curve of the wings develops lift that helps keep them in the air, especially at low speeds. Boats move at similarly low speeds, so boats that are fast upwind have deep fin keels that are fairly short on their chord, front to back. Developing lift in a long, shallow keel is more difficult. Water flows from the high-pressure side, under the keel, to the low-pressure side since the length of the keel (and it’s relative short depth) provide more opportunity for this than a long, narrow foil. The hull also interferes with flow on the keel surface. As an example, supersonic planes have long, backswept, “delta-shaped” wings. This design helps them cut the sound barrier and provides sufficient lift at high speed to keep them in the air. Your long keel is like the supersonic plane’s – but there is no way your boat can move fast enough to make it provide much lift. In fact, imagine a Concorde with wings 100 feet long but only 20 feet wide. It would not get off the ground. That is sort of what you’re dealing with, at 6 knots instead of 600.

[Michael Norman]

Hi Paul. I get what you are saying. It maybe just a function of the design and I should stop fretting about it. Interestingly my previous boat was a Laurent Giles Atlantic 40. A beautiful boat that took me on an Atlantic Circuit. The keel design was similar to my current boat. Guess what, it didn’t win any prizes for pointing either.

I will probably go with a change to a genoa if only to make sail handling easier. I’m not getting any younger. Thanks for your help.

Mick

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