I have a mainsail from a 1971 Cal t4 1/4 ton and it seems to have a sewn in addition just above the foot to make the sail fuller. Is this normal for mainsail construction or is it specific to the IOR boats of the 70's? I am new, so apologies if this is a dumb question or if I have posted in the wrong forum section or something. Thanks
Mainsail foot mod question
- Thread starter Backwaterdog
- Start date
It looks like it could be a “foot shelf”. That’s basically have a loose footed sail but with an extra piece of cloth at the bottom that sits in the groove on the boom. That extra piece of cloth isn’t really carrying any load, it’s just there to prevent air from spilling from the windward side around the bottom of the sail to leeward. In theory that increases efficiency a little bit.
That is an older sail and it was common practice to have a shelf in the foot. Lately the trend has been towards loose footed mains in which the sail is only attached at the tack and clew. Because there is less friction on a loose footed sail it is easier to shape with the outhaul. Shelf footed sails were good at catching water and dumping it the crew during a tack.
Easy to modify to loose foot, clearly with today's practice the 'end plate' effect has been deemed neglible..
That's the term I couldn't think of this morning!
Welcome to SBO Backwaterdog. Congrats on the wisdom in choosing a Lapworth designed boat.
Looks like a one year build boat by CAL. 238 boats between 1971-1972. Not one I have seen. They did that quite a bit in the 70's looking for a sweet spot to sell boats.
Footed sails so that they were easier to flake on the boom was the rage in the day. Not a problem. When I acquired new sails I got the main loose footed. Just left the boom with the track and enjoy the additional sail trimming options. This did create a a need to capture the mainsail when I drop it. I added lazyjacks to serve as replacement for the "foot shelf".
Looks like a one year build boat by CAL. 238 boats between 1971-1972. Not one I have seen. They did that quite a bit in the 70's looking for a sweet spot to sell boats.
Footed sails so that they were easier to flake on the boom was the rage in the day. Not a problem. When I acquired new sails I got the main loose footed. Just left the boom with the track and enjoy the additional sail trimming options. This did create a a need to capture the mainsail when I drop it. I added lazyjacks to serve as replacement for the "foot shelf".
I don't know about making the sail flake more easily, but the shelf foot provides the same kind of easily adjusted draft depth that a loose footed sail does. It is an added feature you can request when ordering your mainsail. It's more common on offshore cruising boats now a days. In order to experience the benefit of the shelf foot mainsail, your outhaul gear should be in good working order. The extra panel of lighter weight sail cloth (the shelf) is designed to fold into the foot of the sail when flattening it with the outhaul. When easing the tension on the foot, the extra cloth unfolds, allowing the mainsail's draft depth to increase effectively.
With a shelf footed sail there was often a cringle in the leech about a foot or so above the clew. That was used in conjunction with the cunningham as a "flattening reef" to take out the extra material in the foot when you wanted to flatten the main.
As others have said it has kind of gone the way of the Dodo.
Thanks for all the replies and great info. North Sails also said that it is a foot shelf and that the boltrop may be stretched out and causing the sail to be overly full. I am going to look into converting to a loose foot main or purchasing a new main soon. There is limited information on the T4, but it appears that Bill designed a modified Cal 25 to compete in the first 1/4 Ton IOR race if I remember correctly. I will post some pictures of her at some point. I have lots of other questions and I look forward to everyone's advice and knowledge.
I think that is correct. The T4 is distinguishable by its very different cabin house..