Got leeches?

[Mark Prouty]

can disrupt laminar flow.

Damn! Now I gotta look that one up.

laminar flow

[Tripp Gal]

Yes, we were out sailing. The women's team is getting ready to head to Victoria for the women's keelboat championships at Royal Victoria YC.

Shock is giving you great information on leech lines. One of the things you can do on a light air day to see what a leech cord does is to try it out.

Hoist your sail and take a moment to ease the leech cord all the way out. sight up under the boom (if the mainsail leech cord is being experimented with) and note the shape of your sail. You should see a nice shape with the draft (deepest) part of the main right about 40% back from the luff. If you had a masthead rather than fractional rig your draft would be about 45%.

So now that you are looking up and you sight that the draft is about 40% look towards the trailing edge/leech of the sail. Ultimately you should see a nice smooth, flat exit on the leech. If it appears the leech is cupped then the leech cord is too tight. If it appears that the leech is falling or folding back away to leeward, then the leech is too loose. You will notice while making changes to the leech that your speed will go up and down. Take notes and adjust accordingly, but do keep in mind that varying wind conditions will require a small adjustment to the leech, expecially with dacron sails.

Here is an example of proper leech cord tension.

I will see what I can do about making a "What not to do" photo for you. I have a practice main that has exhausted it's shape life, and it has a blown out leech, so to stop the fluttering you have to pull on the leech, but then it cups the sail and it can easily slow us down almost half a knot.

[bscott]

I'm standing by my experience with stock Doyle sails---a little flutter (not flapping) is better than a curl-----the sail is not sewn strong enough to maintain any consistancy and with short handed crews that are typical with Macs', sending the first mate up over the cabin top to constantly adjust leach tension just does not work----furthermore, the faster the Doyle wear out and replaced with a quality head sail, the better for all concerned.

And since the topic of depth of cord has been raisen, it is almost imposible to control the cord depth on a 26X because it does not have a mid boom traveler, or a powerful vang, a back stay adjuster, or halyards that are easily adjusted unless the crew goes to the mast. The rigging is almost imposible to adjust while under sail. This is a cruising boat that needs alot of additional sail controls and better sails if it is going to be converted to a racer.

[Frank C]

. . . replaced with a quality head sail, the better for all concerned. . . it is almost imposible to control the cord depth on a 26X because it does not have a mid boom traveler, or a powerful vang, a back stay adjuster, or halyards that are easily adjusted unless the crew goes to the mast.

Hey there, bscott! Nice to have an owner aboard who can add Mac-specific advice. But, few Mac owners are trying to race - or they'd have picked a different boat, yes?

However, many Mac owners ARE interested in learning more about sailing and improving their own boats. Lots of owners have added the sail controls you mentioned, and a couple of guys have enen added travelers. Regarding your list, my boat has:

New UK 135 Genoa (before the Dacron wore out)
Forestay shortened by 4 inches
Split adjustable backstay
Outhaul improved, 4:1
Garhauer rigid vang, 12:1
Main halyard led to cockpit

I have a Harken traveler in the workshop ... but still haven't decided on mid-boom (companionway) or 3/4 boom (across the seats at pedestal). Also, in the works, I'll probably replace the mainsail a'la Steve Kennerly. Finally, I'm convinced we could modify the CB trunk and gain a bunch of performance. And, simple intuition tells me that Tripp Gal is absolutely correct ... if we had our own OD group, we'd probably get really pumped up about performance.

[TonyHouk]

Hey Frank,
I am thinking about tightening up my centerboard trunk. What are you thinking about in the way of modifing it? Thanks and happy sails, Tony

[bscott]

I raced J-24 and Capri 25 one designs with strict class rules. It would be pretty hard to establish an OD for the Mac as there is so much to modify that all boats would have to be precisely the same. Frank, you and Tony are real sailing enthusiasts and have done many of the things necessary to make the boat fast and safe. I have sailed all the Macs as crews and am currently selling my Capri 25 to purchase my own X or M so I have watched these threads with great interest. Kinda like a mini Looper without the powerboat experience. Sail trim has always been the most fun for me as race strategy is better left to the more aggressive owner. My wife will not race anymore and prefers the motoring side of the X/M with the grand kids aboard.

This is an excellent web site with alot of good info shared by all. Bob

[Frank C]

. . . to purchase my own X or M so I have watched these threads with great interest. Kinda like a mini Looper without the powerboat experience. Sail trim has always been the most fun for me as race strategy is better left to the more aggressive owner . . .

Bob,
Careful w/ that simile, doubtful you're Loopy at all. If you wish, you can add some personal info into your profile, using signature or other areas.

Tony,
CB trunk has been debated a lot. Somebody actually created an animation of an articulated cover plate that would be pulled down to fill the gap as the board drops. I've theorized a simple vinyl gasket glued to the hull bottom. If your boat is slipped, Phase I would be to drop the board, stuff the gap with foam or styrofoam, and get out for some testing under sail. If it adds a bunch of performance (I think it will) then you can move on to Phase II prototyping.

[Don B]

I think my boat in the slip is approaching Phase I just from marine life growth. I don't get that satisfying clunk when I pull the board up.

And yes it was bottom painted last year as well as Gel coat protected.

-Don B

[Dimitri-2000X-Tampa]

I tell ya, all it takes is one good grounding on a sandy ground to scrape the bottom paint off. And after just having touched up all the paint around my CB recently, I have a new theory about this. My theory is due to the fact that the upper part of the trunk looks like its never been painted...yet the boat has spent years in the fouling Florida waters.

My theory is that critters won't crawl up the CB (and trunk) if the flat (hull) area around the CB is well painted. I believe this is because many of the critters attach lower down and then crawl their way up to the water line....if the bottom is painted, they never attach there and crawl up into the trunk. Now this is just an uneducated guess, so you marine biologists out there can correct me if I'm wrong.

The reason I think this is true is because I didn't have CB fouling problems (had the nice CB clunk) for several months until my boat got grounded in the sand in April. A few weeks after that, I had lost 3 mph off of my top speed and I knew it was time to take the boat out. Besides the loss of top speed, my CB got stuck in the down position for a while, and was also getting harder and harder to pull into the trunk...it would get stuck just outside of it...and no more clunk when pulling it up either....more like just the feel of mush.

So, pay attention to your CB sounds and feel, it will tell you a lot about the condition of the bottom. One of these days, I'll remove the board and paint the whole trunk...twice. But until then, I just use a little sponge on a stick paintbrush and shove it up into there...getting paint on about 60% of the way up. This is also what I did during summer 2003 and it lasted pretty well until I ground the paint off this spring.