Sloop to cat rig conversion.

[JimD]

Been spending my spare time this past week taking a saw to my daysailer, rigged as a fractional sloop with bowsprit. I have designed a junk sail, built a small one out of polytarp to see if it works more or less as planned and am now at the point of no return with converting the boat to a single junk sail. The junk sail will be about the same size as the jib and main combined. The lead will be the same also, although the CE will be a little higher. Any final words of wisdom from the forum before build the new tabernackle in the eye of the bow to take the new mast?

[paladin]

if it's an unstayed rig yure gonna need some reinforcement in the front (the pointy end)....and with a short bowsprit the bobstay will need to be considerably heavier than the forestay.....

[JimD]

I will glue and screw more wood in the pointy end. The mast will be unstayed, being somewhat shorter than Cambria's. Haven't yet decided on a solid mast or hollow birds beak. Yesterday I cut the old cabin off. It was too big. New one will be quite minimal even for a small boat. It will be tall to provide decent sitting headroom but will be significantly narrower to allow for wide side decks. The back three feet or so of the cockpit will now be mostly taken up by a motor well for an outboard. I cut a hole in the bottom of the boat back there and I gotta say that was fun.

[paladin]

If you shorten the spar....add 15% to the diameter and shorten it appropriately for the new sail....make a birdsmouth with a 20% wall.
What is the proposed sail area.....or what is the length and beam of the boat......and is she ballasted or centerboard....if it is to be a cat rig, is it gaff or marconi...

[TimothyB]

Since it's a small boat, you should be able to find a small spruce sapling somewhere, no? That would be a lot easier than gluing up a hollow mast and would be reasonably light. You could certainly shape it to the dimensions you needed pretty easily as compared to the whole epoxy gluing up a mast process.

I'm assuming you know about the junk sail design program, Sailcut8?

http://www.sailcut.com/

That should help a bit as well. I don't know how you plan to rig the sail, but considering the differences between the original rig and the junk rig you should probably spend some time thinking about how you'll place the sheet(s). There are many ways, including all separate and various combinations of consolidation. Also, if you desire more control over sail shape, you could extend the last top batten beyond the sail plan, far enough to be able to incorporate it into the sheeting arrangement, as does the sunbird rig (http://www.ennui.net/~timothy/Boats/Junk/mayflower/www.btinternet.com/%257Emayflowersc/mscimages/opens/junk/06030006.jpg. That is, assuming your sail plan has the top batten at the sort of angle that usually precludes attaching anything to it... if it is a flat, squarish junk sail (aka a Van Loan style - http://www.friend.ly.net/~dadadata/junk/tutorial.html#Van%20Loan ) then that wouldn't be as much a problem.

[paladin]

oops...sorry...junk rig...:D

[JimD]

Actually, I did not know about sailcut.com. Too late now. I designed it the old fashioned way. It is based on the irregular fan and in general looks something like this with about half as many battens:

http://www.friend.ly.net/~dadadata/junk/Audemard.gif

I decided on the shape starting with aesthetic considerations - I liked the look of it - and then fine tuned it using Practical Junk Rig by Hasler and McLeod.

It will be about 134 square feet. The boat is 15' x 6.5', vee bottom, about 300# ballast, 120# in the steel plate centerboard, 180# inside. The mast will be unstayed, pivot stepped in a tabernackle about 3 feet aft of the stem. The mast will be about 18' long, which is also the height from the deck of the peak of the yard.