Here are some pictures and a quick write up of the sprit sail I made last year for our spindrift. One picture shows the sail furled up by letting the snotter go and wrapping the sail up with a bungee. This is from short camping trip we took at the west end of Kamloops lake last weekend.
I wanted to have something that would:
Use a short mast and spar that would be easy to pack up and haul
Be quick and easy to set up
Be easy to sail
Be easy to get out of the way if I wanted to stop and fish
Be easy and cheap to make with readily available materials - this was a "proof of concept" and not intended for long term use
was interested in a balanced lug rig (and still am) but had trouble figuring out how to do it. In the end I read more about sprit rigs and, after getting a bit hooked on some of those youtube videos of Thames barges, decided to give one a go. Since it is an experiment I've used very cheap materials and I'll see how the set up lasts, then replace it with some better when I've learned more about it. For the first go I downloaded the free plans for the D4 dinghy (http://bateau.com/freeplans.php), and scaled up the sail dimensions to get a sail area about the same as the stock sail. I got a decent quality tarp from Princess Auto, laid it out using the existing edges where possible, then used double sided carpet tape to make the remaining hems. When I was all done I did sew the edges, but I'm not sure that was necessary or better - the carpet tape was pretty good stuff. I reinforced all the corners with three additional plies.
I got two 12' 2x4's from a lumber yard, ripped four square sections from them and glued them together to make the mast. I used titebond 3 to glue them. I made the mast round with a plane and spokeshave. The bottom section where the mast fits into the boat got lots of attention and is pretty round, the rest of the mast got eyeballed. The sprit is the remainder of one of the 2x4's the mast is made of, the snotter passes though a hole near the end of the sprit then is fastened to a clam cleat a little ways up the sprit - it hasn't come loose yet.
Initially I used some cheap blocks from Princess Auto for rigging, but I've since started using a couple of nice blocks I got from a real sailing store, quite an improvement! So I have about $70 in the two blocks, and $45 in the tarp, wood and cordage.
1. At first I didn't check sail's centre of effort. I have done since, and it is further back than the stock sail design. Though it is not terrible, I do find the boat tends to round up in gusts a little more than it really should.
2. We reefed the sail by connecting the sprit to a grommet halfway down the leech, then bungeed the peak to the tack. This arrangement worked well, but the wind quick got weaker and the reefed sail shape was not very efficient.
3. The loose footed sail is great in flukey winds when you want to row for a stretch and leave the sail in place. Also good for sailing with little kids that don't appreciate getting wacked on the noggin.
4. The loose footed sail has a lot of twist. I don't have the experience to say what effect this has on performance but we did make almost five knots with one adult, one child and camping gear. I may try adding a sprit boom at some point in the future to see what difference that makes.
5. The rig is very quick to set up and take down, and easy to brail up if you want to stop to fish, for lunch etc.
6. So far this is working really well for us and I would do it again, but next time I will pay more attention to COE, and will probably get something from Sailrite that isn't green on one side and brown on the other. At the time I chose the better quality tarp over the better looking one!
7. I did this as an experiment, but both sail and mast seem to be wearing well. I used them all last summer, and I expect to get this summer out of them too. On average I get out about once a week from May to September. I sail on lakes and rivers in interior BC, and don't sail in very high winds.
I hope this has been of some interest and/or use.