Bulkhead fillet material

[Napa Ed]

I spoke with a surveyor ragarding the tabbing of bulkheads I replaced this season. To avoid a hard spot along the contact between the hull and bulkhead, he suggested a preformed rubber product that is placed between the bulkhead and hull. The profile of the extrusion provides the fillet shape to be glassed over while the material offers a little cushion as the boat flexes. I have not been able to locate the item online. I do have a call into the surveyor but thought I would ask here also if anyone has experience with such a product or suggestions. I do not want to fillet the joint with thickened epoxy or similar.

 

[Ross]

Do you have an objection to polyurethane?

I would tab the bulkheads in place before filling the gap. When the tabbing was cured I would drill 1/4 inch holes in it at intervals and pump polyurethane caulk in until it came out the next hole. I would work the entire bulk head that way. When I was finished my bulkhead would be well tabbed in place and bonded with a strong adhesive caulk.

 

[Larry Wilson]

bulkhead fillet

Ross's suggestion is good in theory, but in practice? Along with the benefit of padding the hull, the fillet rounds out the corners, making a clean joint.Using the caulk won't do that. Fiberglass doesn't like sharp corners, thus the need for something to ease the angle. When I rebuilt my Columbia Saber I used the closed cell foam pipe wrap, cut into strips and glued to the bulkhead edge. They can be trimmed to make a good clean fillet, and are flexible enough to avoid hardspots. Lowes sells it for insulating air conditioning return and condenser lines.

 

[Ross]

Larry, just as you stated fiberglass doesn't like

sharp corners. So form the tabs without forcing them and you will have a distinct gap in the joint. This is what gets filled with urethane caulk. Of necessity both sides of the bulkhead must be glassed for this to work. I have installed bulkheads in this manner and with Airex core. I prefer this method. The great advantage of this method is the bond between the hull and the bulkhead made with the urethane caulk.

 

[Napa Ed]

reading material

Poking around the web. Found this; http://www.yachtsurvey.com/HullFailP2.htm also; http://www.yachtsurvey.com/Screwit.htmThe surveyors eyebrows raised when he saw that the ODay deck/hull joint was screwed. Now I understand.

 

[patrick]

more plastic

i just used bondo in the joint. used a piece of pvc pipe to make the filet. scuffed it up and glassed over it.

 

[Ross]

The links in Ed's post are examples of

boat building controlled not by boat builders but by marketing and accounting departments. When you read books written by the early builders of fiberglass boats they admit that they didn't know just how strong fiberglass and polyester resin was so they built to wooden boat standards. Most of those old boats from the late fifties and early sixties are still in service. Soon after that they started to trim the laminate schedules to see how much thickness was really needed. Stringers were cut from cardboard tubes and glassed over to add stiffness. Corrugated cardboard was used in some places and not completely concealed. But just as there have always been competent and incompetent builders of everything they are also in the boat building business. If you spend too much money on materials your profit is too small for you to stay in business. If you skimp on materials then your product is junk. Some low-end powerboat builders spray up a gel coat, then a bonding coat and then lay glass in with a chopper gun, compact that layer and lay ONE layer of woven roving over that and then paint it. The deck goes on like the lid on a shoebox and is fastened with pop-rivets. I saw one that is abandoned, backed into by a truck, the side was stove-in without moving the boat from it's place.When we decide to repair our boats we should also make every effort to correct the faults of the builder.

 

[Ross]

The great stuff foam is wonderful but

does not have enough shear strength to transmit loads from the stringer to the hull. That isn't a problem just get enough glass in the stringer and use the foam as a form. My Islander was provided with a hull-deck joint consisting of an in-turned flange on the hull ans an out-turned flange on the deck. The two were bedded in putty, fastened with rivets and a thin wooden rubrail fastened with sheet metal screws ( Well they were stainless steel ). The inside of the joint was glassed. I removed all of that mess on the outside, ground the meeting joint fair and ground the gel coat back about 8 inches and glassed over the outside. Then I ground that smooth, faired it and when it was acceptable I painted it.

 

[Ross]

Ed, I think you've got it.

The boat will be stronger when you finish than it was hen you bought it.