1986 Outrage 18 Bow Chock Removal

[Don SSDD]

[On a 1986 Boston Whaler OUTRAGE 18 boat is] the aluminum bow chock held on with a bolt and nut?

In trying to remove [aluminum bow chock on my 1986 OUTRAGE 18 boat to permit] replacement [of the] rub rail, the fasteners broke off and appear to be bolts. Is there a nut inside the hull? Can I drill and tap and use a new bolt?

Thanks--Don

[jimh]

DON--I think you are trying to describe as "bolts" what are generally called machine screws.

It is common that Boston Whaler imbeds reinforcement or backing material made of WHALEBOARD, which is a trade name for a phenolic board, usually melamine G-8 or something similar. Material of this type is capable of being threaded and tapped to hold machine screws.

In my experience, it would be very unusual for Boston Whaler to just imbed a nut fastener inside the hull. It is more typical that Boston Whaler imbed some strong material, like WHALEBOARD or phenolic board, and use machine screws to fasten to it. Use of machine screws is particularly common when very high strength is needed.

It is also possible that the imbedded material is an aluminum plate. If the screw was stainless steel, there could have been some galvanic corrosion between the two metals.

To get an authoritative answer, you should contact Boston Whaler customer service, give then the stencil number of your hull or the federal hull identification number (HIN), and let them give you advice on this problem.

I think you likely will want to get out the old fastener as the first step in refurbishing. If the broken fastener is a steel machine screw that was threaded into an aluminum backing plate, you will probably have a battle on your hands. Approach this with some solvents and perhaps very cautiously applied heat--but not from a torch.

ASIDE: are you sure the mooring line chocks are made of aluminum? Usually fittings on a c.1986 Boston Whaler boat would be made from some sort of marine grade material, sometimes the trade-name material Marinium, or perhaps a chrome-plated material that was cast to form.

[Don SSDD]

Thanks Jim, I was not familiar with marinium, it just looked like aluminum to me. After your post, I googled the word and found out what it was and also found this old post.

http://continuouswave.com/ubb/Forum3/HTML/003272.html

My stern rub rail caps are made from the same material as well as the hawse pipes in the teak.

Two of the Phillips-head machine screws are broken off flush with the deck and will need to be drilled out carefully. My plan was to use a smaller drill to start the process in the center of the broken screw and drill and tap the hole for one size up screw. Assuming the embedded material is aluminum, Whaleboard, or something like a melamine, this should work?

Any [problem] with using a stainless machine screw to refasten? And some anti-seize, to keep the galvanic action from happening again?

Thanks,
Don

[Phil T]

The backing material in the 1986 Outrage 18 bow below the bow bitt is aluminum plate. Most members attempting to remove the screws find them frozen due to the plate having slightly corroded.

An impact driver is the recommended tool to use in the attempt to remove.

If there is a broken fastener, it is recommended that you drill out the machine screw.

[Don SSDD]

Thanks Phil.

[jimh]

MARINIUM was a trade name for some sort of metal, perhaps just a particularly well-suited alloy of aluminum. I really don't know the metallurgy. More information about MARINIUM from PERKO is available at their website.

Regarding prevention of seizing of stainless steel threaded fasteners, see the FAQ for some advice:

http://continuouswave.com/whaler/reference/FAQ/#Q8

Read the first paragraph and follow the hyperlink at the end of that paragraph to more information. In general it is a good idea to use some sort of specialty compound on stainless steel fasteners to prevent seizing or galling.

There are several LocTite products available.

[Don SSDD]

Thanks Jim.
Don