Older 13-footer: Raising Transom to 20-inch from 15-inch

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
cajun dave
Posts: 3
Joined: Sat Apr 21, 2018 8:56 am

Older 13-footer: Raising Transom to 20-inch from 15-inch

Postby cajun dave » Wed Aug 01, 2018 8:58 pm

I bought a 1972 13-footer that originally had a 15-inch high transom that has been raised to 20.5-inch high with a 2x4 or maybe 2x6. The [fiberglass or resin adhesive on the modification to the transom] was not adhered well so I removed it with a grinder to bare wood.The wood shows no signs of rot but I can’t figure out how it’s attached to the original hull transom. It’s solid with no movement whatsoever.

I’m planning to coat the wood with polyester resin and add layers of 1708 to tie it in to the existing glass on the transom. It will support a Mercury 40-HP FOURSTROKE outboard with trim-tilt, about 260 lbs.

I have sent a request to Boston Whaler support asking for advice on a recommended procedure or technique they suggest for raising a transom and any drawings. I would think this is a fairly common modification.

Other than wrapping [the previous modification] in glass, what would one do to insure the integrity of the modification?

If glassing is sufficient how many layers of 1708?

Any suggestions appreciated

ConB
Posts: 248
Joined: Fri Oct 09, 2015 2:52 pm
Location: Suttons Bay, MI

Re: Modifying a 15” transom to 20”

Postby ConB » Wed Aug 01, 2018 9:31 pm

When I raised the transom on my 13' Whaler all wood laminating, fiberglass mat laminating, and faring was done with West System Epoxy.

I would not waste my time with polyester resin for that type of job.

Does the wood match the curve of the original transom? Hard to tell what is holding it together. I laminated 1/2" stainless pins into mine. 1708 biaxial cloth should work but I'm not an engineer so my guess is two layers.
!987 Outrage 18 / 2011 Yamaha F150
1969 13 / 30hp Johnson tiller

jimh
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Location: Michigan, Lower Peninsula
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Re: Older 13-footer: Raising Transom to 20-inch from 15-inch

Postby jimh » Thu Aug 02, 2018 7:48 am

Preserve the original stencil number on the inboard side of the transom.

WEST System epoxy will be a stronger adhesive for bonding to the cured fiberglass on this older boat than polyester resin.

Raising the transom height to 20-inches is a common modification, but there is no particular method in universal use.

cajun dave
Posts: 3
Joined: Sat Apr 21, 2018 8:56 am

Re: Older 13-footer: Raising Transom to 20-inch from 15-inch

Postby cajun dave » Mon Aug 06, 2018 9:09 pm

BW says I have a 71 sport according to the serial number. Is there a source for center consoles for these small boats. I purchased a 40 hp merc, 2011, from a dealer that has 0.5 hours on it. It’s a little heavier than I want but couldn’t pass up new motor with tilt and trim for $3300. I’ll need to install controls and steering. The dealer quoted about $1300 installed for all that with a tach.

Since I’m modifying it it won’t be vintage. I’d prefer the tan color interior with flattening agent which will need to be completely painted due to condition. Probably use Soft Sand for non skid. I don’t have experience with spraying and don’t have a large enough compressor so I think I’m own to 2 part paint roll and tip. Any suggestions on suppliers for the color I want. I’m laying two layers CSM to the complete interior. Exterior will be white or off white. It’s in pretty good shape but won’t really know till I turn it over. Any tips or advise would be appreciated from this rookie boat refinisher. Thanks