Questions on Keel-Band Attachment

[Ken Leap]

I am preparing to attach a 1" x 1/8" flat bronze strip to the backbone (stem to stern) of my 19'6" Caledonia Yawl, "Reina del Llano."

(1) What screw size is appropriate?

(2) What is a proper screw spacing?

(3) How shall the holes be sealed?

(4) Is a bedding compound or special surface preparation recommended? (The stems will be finished bright above the water line and painted below.)

(5) I know from experience with other work that I must bend the bands before drilling the holes. Any other advice for this job?

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

[ 04-06-2005, 08:54 AM: Message edited by: Ken Leap ]

[JimConlin]

I'd use #12 flat head bronze screws at 3-4" spacing and use Dolphinite or another traditional bedding compound. Do this after all painting & varnishing.

[Mike Field]

.
I'd do what Jim says (although I think you could increase the screw spacing a bit, except at the sharper curves.) I also think your Point 5 is about the most important thing of all.
.

[Ken Leap]

Thank you for the advice on the bedding compound. I googled Dolphinite for some detailed information but found that their site has disappeared. Other 'hits' gave me some information but also raised more questions.

I learned that Dolphinite has the consistency of peanut butter and can be applied with a grooved trowel. This makes me wonder about the final thickness of the bedding layer. I was going to fit and pre-drill backbone and keel band before painting the bottom and applying the Dolphinite. Now I wonder if I need to allow for the thickness of the bedding before drilling holes.

What is a typical thickness for this application?

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

[ 04-06-2005, 05:56 PM: Message edited by: Ken Leap ]

[JimConlin]

Bedding compounds are available where boat stuff is sold. I generally buy it from Jamestown. It squeezes out easliy and the amount left in the joint is negligible.

[kc8pql]

Originally posted by JimConlin:
It squeezes out easliy and the amount left in the joint is negligible.In fact you would do well not to screw it down to hard so you don't squeeze it all out. It doesn't do any good if it's not there. Another method is to use 3M 4200. Screw the band on but not to tight. Let the bedding set up for a few days and then go back and tighten the screws. The hardened compound will compress and form a good seal but won't all squeeze out.

[Tristan]

I have used 3M 5200 for this same sort of job. Squeeze some 5200 onto the screws too, that'll get it into the predrilled holes. I feel that Dolfinite is too expensive and not as good as the 5200. Of couse with 5200 you'll play hell getting the bronze strip off if you ever want to later on.