I'm restoring an ancient13-footer with a hull number in the 4000s, which should make it a 1960.
The lip on the bottom of the gunwale seems to have been formed over something ferrous, perhaps a spiral conduit like BX cable or similar judging from the traces it left behind. It has of course rusted away completely, leaving a hollow core of rust inside the gunwale, except in the places where the gunwale has collapsed and there's just rust-stained foam. (in those cases it collapsed from the bottom or side - the top side is fine)
Give me advice on how to remove the rust stain and repair the gunwale laminate.
plan to slit the side to get access, vacuum out the bulk of the rust, put in rust neutralizer, then foam, and then laminate over the repair area, I have no experience dealing with a repair like this.
Also, note I'm going to be installing the more modern three-part rub rail, rather than the old one-piece rubber one.
Older 13-footer Has Rust Inside Gunwales
Re: Older 13-footer Has Rust Inside Gunwales
Your analysis that the source of the rust is from a metallic spiral electric cable is correct. Boston Whaler used BX-cable in the early 13-foot boats.
I don’t know the precise reason for the use of the steel-sheathed cable, but I believe the spiral metal sheathing had something to do with venting air from the process of filling the hull with foam. Bob Dougherty described this to me in person once while we were chatting at a boat show years ago.
The remedy you propose sounds very workable. But you should experiment with the “rust neutralizer” first in a small area to see if there is a need for it and if it causes more harm than good. Perhaps you can find some paint that will help stop future rust. Instead of foam you could use epoxy resin thickened with a low-density filler. Then use epoxy resin for the lamination and top coat, adding white pigment to the resin for the final layer.
ASIDE
The use of the BX cable might be correlated to the boat being developed in Massachusetts. I seem to recall that back in the 1950’s the electrical code in Massachusetts may have allowed or preferred a metal-sheathed cable to be used instead of the now more common Romax cable for house wiring. But that is just a guess based on a vague recollection, and seeing it used in homes in the New England area.
I don’t know the precise reason for the use of the steel-sheathed cable, but I believe the spiral metal sheathing had something to do with venting air from the process of filling the hull with foam. Bob Dougherty described this to me in person once while we were chatting at a boat show years ago.
The remedy you propose sounds very workable. But you should experiment with the “rust neutralizer” first in a small area to see if there is a need for it and if it causes more harm than good. Perhaps you can find some paint that will help stop future rust. Instead of foam you could use epoxy resin thickened with a low-density filler. Then use epoxy resin for the lamination and top coat, adding white pigment to the resin for the final layer.
ASIDE
The use of the BX cable might be correlated to the boat being developed in Massachusetts. I seem to recall that back in the 1950’s the electrical code in Massachusetts may have allowed or preferred a metal-sheathed cable to be used instead of the now more common Romax cable for house wiring. But that is just a guess based on a vague recollection, and seeing it used in homes in the New England area.
Re: Older 13-footer Has Rust Inside Gunwales
Figure 1 shows rust, looking down with the boat flipped. The starboard side doesn’t have any wiring inside the housing; not sure about port.
I don’t know when BX cable was banned in Massachusetts, but it was used in the vast majority of houses here that were electrified after construction, except for a few of the fanciest places (i.e. first to get electricity) which were wired with knob and tube.
BX sheath would have been a readily available and cheap material back then, and I doubt Boston Whaler were worrying about how it would hold up after 65 years when it was only their second or third year of production.
- Fig. 1. Rust stains.
- IMG_6437.jpeg (53.57 KiB) Viewed 409 times
I don’t know when BX cable was banned in Massachusetts, but it was used in the vast majority of houses here that were electrified after construction, except for a few of the fanciest places (i.e. first to get electricity) which were wired with knob and tube.
BX sheath would have been a readily available and cheap material back then, and I doubt Boston Whaler were worrying about how it would hold up after 65 years when it was only their second or third year of production.
Re: Older 13-footer Has Rust Inside Gunwales
I don’t think the BX cable sheath had electrical conductors in it.
There typically was a flat two-conductor zip-cord type cable that was run to the bow and concealed under the rub rail, but I don’t know for sure if really old 13-foot hulls would have that, as those hulls tended to have a one-piece white rub rail that was attached with adhesive to the hull.
There typically was a flat two-conductor zip-cord type cable that was run to the bow and concealed under the rub rail, but I don’t know for sure if really old 13-foot hulls would have that, as those hulls tended to have a one-piece white rub rail that was attached with adhesive to the hull.
Re: Older 13-footer Has Rust Inside Gunwales
Wiring [for a navigation lamp] was run through the hull in pre-72 models as mentioned in the FAQ at
https://continuouswave.com/whaler/reference/FAQ/#Q4
On my boat at the spot where [wiring embedded in the hull] would exit for a [combined sidelight navigation lamp at the bow] I just see a brass plug.
And you're right: the old rub rail couldn't hold wiring because it had an L-shaped cross section and was glued on.
https://continuouswave.com/whaler/reference/FAQ/#Q4
On my boat at the spot where [wiring embedded in the hull] would exit for a [combined sidelight navigation lamp at the bow] I just see a brass plug.
And you're right: the old rub rail couldn't hold wiring because it had an L-shaped cross section and was glued on.