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View Full Version : Stempost Configuration for Caledonia Yawl



Ken Leap
02-07-2005, 12:59 AM
I am building Oughtred's Caledonia Yawl, gunter rig version. With input from Moray MacPhail of Classic Marine, I have come up with an arrangement for forestem fittings. The parts recommended by Moray (and shown in Classic Marine's CY hardware list) are the HL-0508 Bronze Pad Eye and the HL-0423 Bronze Bowsprit Plate. See photos of parts below and my proposed setup.

http://www.classicmarine.co.uk/images_products/115.jpg

http://www.classicmarine.co.uk/images_products_large/181.jpg

http://www.kenleap.com/images/cy_fstm_ftng_2_lg.jpg

The bowsprit plate and pad eye share two through bolts. The bowsprit plate has additional fasteners (a wood screw at each end) for a total of four fasteners. This arrangement seems mechanically sound. The bowsprit plate can't be used for any forward pull (e.g., trailer winch or towing), because the upper end may bend or peel off of the stem.

Is the layout of these fittings (as shown above) reasonable? I'm out in the High Plains of New Mexico, don't have any boats to look at, and am always wondering if I am violating some law of aesthetics for classic wooden boats.

Ken

Reina del Llano (http://www.kenleap.com/boat.html)

Banjo
02-07-2005, 05:32 AM
Nice looking fittings!
Couldn't you do away with the pad eye and just use the bow plate? And use forestay clips on your forsail?
Banjo.

Bob Smalser
02-07-2005, 10:55 AM
The hardware layout looks fine to me. That hunk of the stem is critical enough and the stresses great enough that I'd bed those plates and bolts in epoxy so they don't "work" and crush wood fibers in the process. Use paste wax as a release agent for the metal.

http://pic3.picturetrail.com/VOL12/1104763/6490387/84455215.jpg


The bowsprit plate can't be used for any forward pull (e.g., trailer winch or towing), because the upper end may bend or peel off of the stem. Mostly because the angle is all wrong. No substitute for an eye bolt with backing plate aligned with the line of stress.

[ 02-07-2005, 03:29 PM: Message edited by: Bob Smalser ]

Ken Leap
02-09-2005, 11:33 AM
Banjo...Yes, using the bowsprit plate for both the forestay and the jib tack was an earlier idea and one that looks better to me now, thanks to your input and comments from others. Classic Marine also agreed that this would work. I now have to figure out what hardware to use for connecting the forestay and jib tack. Where can I see what a forestay clip looks like?

How is this layout?

http://www.kenleap.com/images/cy_fstm_ftng_3_lg.jpg

Bob...I agree, the integrity of the stempost is critical and the stresses there significant. I like your idea of bedding the plates and bolts in epoxy. I have used paste wax as a release agent in casting sculptures but have never considered it for releasing epoxy and will have to give it a try.

Can more be done to protect the stem? I worry about crushed wood fibers, as you mention, and also delamination of the stem. I think that the laminated stem is vulnerable when stressed at the end. A metal sleeve or tube set in the bolt holes with epoxy is something I would like to consider. Is this practical?

Ken

Reina del Llano (http://www.kenleap.com/boat.html)

[ 02-09-2005, 11:53 AM: Message edited by: Ken Leap ]

casem
02-09-2005, 07:17 PM
I must say that rendering on your website is almost cooler than the real thing.

What do the plans say? On the Whilly Boat the forestay and jib tack attach to a pad eye on the fwd deck (fitted at the lower edge of the shear strake). I bolted mine that way (Whilly Boat) and never had any problems (at least with that).

Ken Leap
02-10-2005, 11:37 AM
Casem,

The rendering was quite a project. I modeled it in 3D partly because I had never seen a Caledonia Yawl before and wanted to be able to view it from all angles.

Back to the forestem...The plans do not specify exactly how to attach the forestay and jib tack. The sail plan indicates some sort of fitting on the breasthook, possibly straddling the top of the stempost, which is shown trimmed flush with the gunwales.

For some reason, I was assuming that the jib would be set flying. Now I can't find any specifications for this. Are any of Oughtred's beach cruisers rigged with flying jibs?

Ken