converting a sloop to a schooner rig

[robwilk37]

can someone steer my to a book or online tool that will help me rerig a sloop to a schooner? how to calculate mast positions and sail(s) area, sprit/boomkin length, center of effort, righting moment, etc... i know she wont go to weather as well and i know theres additional rigging/maintenance expense, but its a lovely rig, and since the boat is rigless now and deck stepped (something i need to change anyway), i thought id look into the conversion. shes a spencer 42, full deep keel, cut away forefoot with a barn door rudder, and im thinking bermuda/staysail (no gaffs). thanks so much...

[cormeum]

You'd need to hire a naval archetect to figure the correct mast positions, make sure the hull will take the strins of having masts not in the designed locations etc. It's a BIG job. If you like that rig, I'd suggest you look for a boat that is already schooner rigged- you'd be happier in the long run.

[JohnRPollard]

Originally Posted by cormeum

You'd need to hire a naval archetect to figure the correct mast positions, make sure the hull will take the strins of having masts not in the designed locations etc. It's a BIG job. If you like that rig, I'd suggest you look for a boat that is already schooner rigged- you'd be happier in the long run.

Agreed.

There are no on-line tools that could do this for you. There are too many variables involved here.

Your second best bet is too hire a naval architect. Better still would be to find a boat originally designed as a schooner.

I think if you try to do this on your own without qualified professional advice, you will have a very unhappy outcome.

Good luck! Let us know what you decide.

[WanderingStar]

I believe it can be done, but will require a great deal of study and effort. You will need to become an amatuer naval architect. Read Chapelle's "Yacht Designing and Planning".

[sailingdog]

As suggested above, it would be far less expensive to sell your current boat and buy a schooner than it would be to modify this existing boat to a schooner rig. All of the chainplates, the deck structure, hull structure would probably need to be re-worked to do the conversion.

[AdamLein]

I wound point out that Joshua Slocum's vessel, Spray, was originally a sloop. Slocum converted her to a Yawl in the Straits of Magellan. So adding masts is, in some Platonic sense, possible. You must remember that Slocum basically was a naval architect; he restored Spray from a rotting hulk.

But a schooner is a different story from a yawl. A yawl really is a sloop with an extra mast. But the position of the mainmast in a schooner is different from than of a sloop, which carries her mainmast farther forward. You'd probably want to move the mainmast back, which would mean adding a compression post, installing new bulkheads to support the shrouds, adding a boomkin to move the backstay to, possibly interfering with hatches... and would likely throw the balance way off in the process.

Speaking of stays, if you add a foremast, how will you stay the mainmast? The forestay would probably get in the way of the foremast boom. You could maybe run a line between the two mastheads, like some ketches have, but you still have the problem of staying the foremast, now compounded by the pull from the main. You'd need a long bowsprit at least.

New bulkheads, bowsprit and boomkin, new compression posts.... how hard can it be? Sounds like some modifications that would be a lot of fun to do on somebody else's boat. If you're in the Vancouver area and want a hand, let me know

[sailingdog]

A yawl is only slightly different from a sloop, and the conversion is often rather trivial. A ketch is a bit more severe a modification, but a schooner basically requires a rebuild.

The way the two masts are usually stayed on a schooner is the forward mast has a forestay as is typically found on most stayed rigs. The after mast is supported using a triatic stay that goes from the foreward masthead to the aft masthead and transfers the forward loading across to the after mast from the forestay. This is one reason when one mast fails on a schooner, the second one usually gets taken down as well.

A bowsprit might not be necessary, as not all schooners have them. The main reason for a bowsprit is to move the center of effort forward.

Originally Posted by AdamLein

I wound point out that Joshua Slocum's vessel, Spray, was originally a sloop. Slocum converted her to a Yawl in the Straits of Magellan. So adding masts is, in some Platonic sense, possible. You must remember that Slocum basically was a naval architect; he restored Spray from a rotting hulk.

But a schooner is a different story from a yawl. A yawl really is a sloop with an extra mast. But the position of the mainmast in a schooner is different from than of a sloop, which carries her mainmast farther forward. You'd probably want to move the mainmast back, which would mean adding a compression post, installing new bulkheads to support the shrouds, adding a boomkin to move the backstay to, possibly interfering with hatches... and would likely throw the balance way off in the process.

Speaking of stays, if you add a foremast, how will you stay the mainmast? The forestay would probably get in the way of the foremast boom. You could maybe run a line between the two mastheads, like some ketches have, but you still have the problem of staying the foremast, now compounded by the pull from the main. You'd need a long bowsprit at least.

New bulkheads, bowsprit and boomkin, new compression posts.... how hard can it be? Sounds like some modifications that would be a lot of fun to do on somebody else's boat. If you're in the Vancouver area and want a hand, let me know

[AdamLein]

Originally Posted by sailingdog

A bowsprit might not be necessary, as not all schooners have them. The main reason for a bowsprit is to move the center of effort forward.

Wouldn't a secondary purpose a bowsprit be to decrease the vertical angle that the forestay makes with deck, thereby decreasing the necessary tension in the forestay? Sort of like how mounting chainplates further outboard reduces the necessary tension in the shroud.

[sailingdog]

Yes, it would. I'd point out that installing a bowsprit would also require adding a bobstay, to offset the vertical loads on the sprit and transfer them to the hull via compression along the sprit itself.

Originally Posted by AdamLein

Wouldn't a secondary purpose a bowsprit be to decrease the vertical angle that the forestay makes with deck, thereby decreasing the necessary tension in the forestay? Sort of like how mounting chainplates further outboard reduces the necessary tension in the shroud.

[klem]

If I am reading the original post correct, he is looking to have a staysail schooner with a marconi main. This means that the mainmast is supported forwards by two stays, the spring stay which attaches to the foremast head and the main staysail stay which attaches near the base of the foremast. The sails associated with this rig are a main staysail and a yankee rather than a conventional foresail.

Bowsprits has some large advantages and disadvantages. They were necessary on most schooners to balance the sail plan since the large mainsail (especially the gaff rigged ones) all the way aft tended to cause a lot of weather helm. If you look at the knockabouts, they had to extend the bow quite a ways to get them to balance so it is almost like having a bowsprit but it is really an overhang. Bowsprit rigging has a lot of failure points because of the bobstay and whisker shrouds. I am a firm believer in having a forestay to the stemhead and a jibstay going to the end of the bowsprit rather than a single stay. There are many examples of failure (especially related to bobstays since they keep getting dunked underwater), the most well known of which caused the recent dismasting of Pride of Baltimore II. I think that bowsprits have many advantages but they must be designed properly. The lower angle of the jibstay does mean that it has less stress.