Chebacco News
Number 27, August 1999
Sylvester anchored in Balmerino bay, Scotland, May 1999
It’s some time since the last Chebacco News hit your postbox/computer. There’s not been a great deal of news from you, so there isn’t much to report. Remember, this is yournewsletter – so keep telling me about progress, voyages, ideas . . .
Sail Trim and Crew Balance on a Chebacco-20
Judging by the email correspondence I get about the Chebacco, there seems to be a nagging worry about sail trim and crew balance. This is entirely understandable, since most of us have cut out teeth on conventional Marconi-rigged sloops. There’s a wealth of knowledge out there about how to get the best out of a Marconi rig, but not a lot on cat yawls. I hope this will help to redress the balance to some extent.
It has been mentioned in Chebacco News before that the mizzen should be cut dead flat – no draft at all. Likewise, when it is set, the snotter should be hardened in to keep the sail flat. Any appreciable draft there will result in a tendency to imbalance. The mainsail, on the other hand, should have good draft, with maximum depth no more than 40% of the chord aft of the luff. You need this to give you the drive to get the best out of the boat.
One other detail about sailmaking – the reefing points should be set more or less in a straight line, to help give a flatter sail when reefed. A baggy reefed sail is unhelpful, to say the least!
Given this as a starting point, then, how do we get the best out of the boat?
Like all catboats, the Chebacco has a beamy hull – not as extreme as some, but still quite wide. This means that as she heels, the underwater part becomes increasingly asymmetrical, with a tendency to round up into the wind. I find that in light winds, I can lash the tiller and steer Sylvester simply by moving my weight around to give more or less heel – so it’s pretty sensitive! The effect of extreme heel is powerful weather helm, which gets to be too much to handle (for me anyway) when the lee gun’l is awash (probably around 20 degrees of heel). It is sometimes argued that a little weather helm is a good thing because the rudder tends to ‘lift’ the boat to windward. On the other hand, it also creates drag and slows the boat down. Certainly large amounts of weather helm are bad.
The trick, of course, is to move your weight, and that of your crew around to keep her sailing almost upright, so the underwater part of the hull is symmetrical. If the wind is still heeling the boat too much, you can help a little by raising the centreboard to about the half-way point, allowing the boat to make a little more leeway, but ultimately a reef (or two) must go in. So if you are sailing single handed, you need to reef sooner than if you have a hefty crew along. I find that a reef is necessary with force-4 winds, single handed, and force-5 with a couple of crew aboard.
I’ve never found the Chebacco to be very sensitive to fore-and-aft trim, though it’s not a good idea to weigh down the aft end so much that the transom drags. If the crew are distributed along the side benches, then you shouldn’t have to worry about it.
Sail trim is pretty conventional – I simply sheet in the sails until the luff is just full. Hardening them in too much is counterproductive and the Chebacco certainly doesn’t respond well to ‘pinching’. She’ll point within 45 degrees of the true wind direction, though taking leeway into account she’s really sailing about 50 or 55 degrees off the wind. Like all boats, the bigger the chop, the less well she does to windward – though she’s a lot better in this respect than most sharpies, for example.
The centreboard also needs a bit of thought. With no CB you make too much leeway – getting blown sideways across the surface of the water. On the other hand, the CB all the way down will resist leeway but add drag. As I’ve mentioned above, it’s sometimes not a bad idea to raise the centreboard a little to allow more leeway to absorb gusts. I find that the Chebacco will sail tolerably well on all points of sail with the board about half way down. For peak performance, though, it should be raised for running before the wind, and all the way down when getting to windward in a moderate wind.
It’s a wonderful experience to have everything set just right. You have a powerful feeling that the boat has settled into a ‘groove’ – She’s smoking along, and only minimal adjustments to the tiller and mainsheet are needed to keep her like that. That’s the kind of sailing that makes it all worthwhile.
Motorsailing a Chebacco
There are times when the weather doesn’t cooperate with your sailing plans – especially when there are very light winds and progress is slow. At such times I frequently ‘motorsail’ Sylvester. I keep the sails up and sheeted well in, start the outboard and set the throttle to a little faster than a tick-over. The hull is so easily driven, especially in flat conditions, that there’s little point in running the outboard flat-out – the tiny amount of extra speed just isn’t worth the extra noise and fuel consumption involved.
If you’ve never done this, it’s a revelation. The small amount of true wind, combined with the apparent wind generated by forward motion fills the sails and provides more drive than the outboard alone would generate; resulting in pointing higher and good progress to windward.
Reprints of classic boating books
David Goodchild is doing some great, excellent value reprints of classic, out-of-print boat books. Have a look at for further details at
http://www.anyboat.com/books/
News from Papua New Guinea
Dick Burnham, currently in Papua New Guinea, sent me his ideas on stopping water from entering the mast hole:
I’ve been whittlin’ away this late afternoon — making the little masts for
the model. This gets me thinking and I’ve also been going over the
CNewletters and studying the details of the mast penetration of the roof.
I’ve noticed that just about all who report on it say they are conditioned
to sponging up the leaks from this joint. I guess a rubberized boot
doesn’t work, especially if one is demounting and resetting with
regularity? Here is what might be a small improvement, I really don’t
know. I’d like your thoughts.
Build out a square collar of wood with epoxy and screws — possibly 2″ —
around the mast so that it covers a raised strip of wood that surrounds the
opening in the roof/removeable panel. This is a curb that will keep water
from the roof out of the hole. I’d think it would be 2″ high and the width
of the 4 individual curb pieces would be 3/4″ or so. (I’ve not looked yet
at the detailing of the curb at the roof/removeable panel joint, so be
cautious….) Water coming down the mast will be diverted outward by the
collar (which would have a slight bevel to the outside) and will drop to
the roof, as there would be a saw cut underneath the collar to stop water
from running back to the mast on the underside.
I looked at the possible problem of the collar being in the way during mast
raising — using a half-completed mast on a model without a cabin structure
— just the molds/bulkheads in place — and it seems that the mast heel
will rest and glide down the inner stem without a collar gouging into the
cuddy roof. Ideally the collar would have a closed-cell foam insulation
strip underneath which compresses against the curbs when the the mast is
set. Or there could be multiple grooves to inhibit water passing through.
This might inhibit driven water.
The collar doesn’t need to be square, but the curb does. The collar could
be circular if that pleases the eye.
The idea comes from the Parker book which I enjoy for its practical
construction suggestions.
Sorry for all the words. As Mark Twain (was it?) once said, I’d have
written a shorter letter but I didn’t have the time.
Dick
And finally . . .
That’s all for this (slim) issue. PLEASE keep in touch and let me have news, views, hints, tips, stories, pictures, . . . There are a lot of people out there who deluge me with complaints when Chebacco News is late. I’d rather have stories, please.
Bill Samson, 88 Grove Road, Broughty Ferry, Dundee, DD5 1LB, Scotland
wbs@sol.co.uk