retractable centerboard

[billdog]

I have a 1986 Seidelmann Sailboat Model S295. It is a 30 footer with a 3' 6" shoal keel.
The keel is retractable into an encasement. The keel has fallen off and been lost at sea.
Seidelmann went out of business in 1986 and was not bought by anyone.
Does anyone know or know where I could find the specs to this centerbord.
Are they similar between boat manufaturers.
Or does anyone have a any ideas

Thanks

[alan white]

They are not the same between manufacturers. My suggestion is you find a sister ship and first ask what material the board is made from.
Then you need to create a pattern from perhaps foam insulation board or thin plywood . This may involve a Travellift to get the boat up in slings for a while. Thickness is critical, with sufficient clearances. It's easy to subtract a half inch from the leading edge, trailing edge, and top, but the side to side clearance should be sloppy enough to allow for various kinds of scum and marine growth which often happens when the trunk can't easily be anti-fouled.
I think I'd want a total of at least 3/8" but others may have their own ideas on that clearance.
The axle or pivot bolt should align your drill to locate that hole, and lastly the cable eye for raising is x number of inches aft of the pivot, and that's where the attachment is made, by one of several methods depending on material.
If steel (maybe the original was iron or steel), it's quite easy to make a new one with a cutting torch, a grinder, and a drill press.

[billdog]

thanks for the reply
I do have some information about the location of some sister boats
I do remember that the old centerboard was fiberglass and had a shape to it
I think the shape was thinner on on the leading edge and the trailing edge .
I am not sure what the core was. I guess it does not matter. I could use what ever would be the best material for the core at his point. I can get a
pretty good idea of the old overall dimensions because I remember how the old board sat in the cavity. I guess I am most concerned with shape and weight of the old centerboard. I would imagine that the board was
weighted more at the bottom edge to make it drop down.
Do you know of a designer or website that could figure the best design for the board. I do have the overall ballast and diplacement specs of the hull
but do not know the split between the centerboard and the stub. Is there a basic formula for ballast split between the stub and ceterboard. My boat was built for speed and is not a blue water cruiser so I would imagine that everything was built as light as possible.
I am sure with some guidance I could make and install a new centerboard.
Thanks

[PAR]

Unfortunately, though there are formulas and other "tools", each design is application specific in regard to board shapes, weights, location plan form, etc. In fact ever aspect of the design will be like this.

It's very likely your board was ballasted, not just weighted and that shapes were well defined. Where are you located?

[alan white]

A lot of times I've had to design parts for which no drawings were available, and nothing to copy. Rudders especially on small boats (the sea floor must be littered with them).
I don't like centerboards on larger boats. They are a pain to access for any maintainance (time consuming and expensive), and so a lot of otherwise well-maintained boats have problems creeping up that aren't being monitored.
The best setups I've seen have a top cover for the case. It's possible to get the board out from above. Controversy sloops had them, and actually, a lot of wood boats with slotted ballast keels did, but few fiberglass boats.
I have replaced cables before and painted the board and case but I had to pay for the slings to be tied up for the required time.
The only sensible answer is a cradle tall enough to allow maintainance, with support fore and aft of the slot.
The height of the board when horizontal shouldn't exceed 18" or so on your boat, and likely less, so I'd recommend you alter your cradle if you use one and allow for getting in there to work, and to regularly maintain the board in the future. A trailer is problematic owing to axles and the roller track in the center, and slings just cost too much unless the boat yard owner is your brother in law.
Frankly, the exact sectional shape of the board is not going to require knowing what that particular boat had, just a shape copied from any good sailing boat's board. Most important is that the angle of the board is correct when down all the way. That is going to be harder to accomplish. You may have to use slings for that and glass in blocking or whatever works, knowing beforehand what the angle is supposed to be based on a drawing from the original design.

[PAR]

It depends on what type of board is employed (slice of pie, high aspect, etc.) as to the plan form, which is often affected by the hoisting arrangements as well.

All my board designs have a removable case top, but it's an over looked item as Alan mentioned.

At the very least, a reasonably accurate sail plan and yacht spec's will be necessary to pen up a new board. Having accurate weights would be very helpful.

[ancient kayaker]

A Google search for "Seidelmann Sailboat Model S295" turned up several sites including this one http://seidelmann-owners.com/S295_ALL/index.html
which will at least give you the basic dimensions and weight from which you should be able to design something suitable to fit your boat. Good luck!

[billdog]

I know about the website. My boat is listed on there. The name is the Virgil.
The website does list the general specs from the original sales brochure.
It does not have specs for the S295model centerboard. I have found out that the centerboard was made of fiberglass and did not have ballast except maybe some and the stern end to drop down. I have had the board down on the lift in the yard to try and inspect it to best of my knowledge the board would drop straight down and was not on an angle. The pin and lift mechanism are all inside
the cavity and not accessable from inside the boat. The local guy who does work on my boat has a theroy that the pin was eaten away by electrolisis?
I was think about just filling the cavity with about 600lbs of ballast weight and leaving it at that?
What do you think?

[alan white]

You know how she sails without the board. But unless the boat was improperly designed, I wouldn't add ballast as you'd lose good cruising capacity and speed too.
I don't know how easy that would be either, probably a lot more work than building a new board.

[billdog]

I have found out that Tartan27 B Centerboard was very similar to the centerboard on a Seidelmann 295CB. Does anyone know where I can get the
specs on a Tartan 27 centerboard?