Transom wood

[Johnny]

matter of factly, Watson - I have tried it.

not only the Baltic Birch but the Northern Fir cabinet grade plywood.

some of the very first signs I made back in the late '70s were birch and fir 3/4" plywood.
I sealed all the edges and surfaces with Danish Oil Sealer.
horrible mix of materials for any kind of exterior use. they lasted less than 2 years. Lesson Learned !!
Through self education and some mentors, I graduated to exterior grade A/B pine plywood
with the 50/50 of Spar Varnish/mineral spirits....... followed by two coats of thinned oil primer
then the top coats of color......
those lasted much much longer with no noticible distortion in a 4x8 panel.
when my business improved, I moved to doing the MDO panels exclusively.

It has been noted here that any kind of plywood will work for a transon as long it
is PRESERVED PROPERLY - with the proper methods that are proven to be effective.
epoxy, fiberglass, varnish and paints all will work if applied correctly.
a project that is time consuming and laborius is not the place to make shortcuts to save a buck.

depends on the usage and storage of your boat. if you only take it out once a month in good weather
and store it inside your garage, the wood will last 10 or more years.
if your boat will be in the elements 24/7/365, then more attention really needs to be
on all the woodwork.

jus my Dos Centavos


Read, Understand and Follow the instructions on the label of all products you use.
Pay particular attention to the safety notes and heed the warnings accordingly.
any rags used in the prepping/painting process that have solvents, oils or paint on them,
should be layed out in the open to completely air dry prior to discarding them.

 

[stinkfoot]

If you don't want to ever do it again, use https://www.kingplastic.com/products/king-starboard/ not plywood.

I'd never use that as a transom material, it has the compressive strength, but flexes FAR MORE than plywood would in a purely 'structural' sense. King Starboard and the like flexes and bends way too much to be an effective transom material.

It also moves with temperature changes, so any fastener hole needs to be up to twiceX that of the fastener diameter, dependent on material thickness and size overall.

I LOVE it for making accessory items, but IMHO it is an extremely poor (and expen$ive) choice for a transom. That said, I have used it to add a 12" square or less 'transom pad' that is centered on the outside of the transom, for the OB mounting, but the transom core itself was plywood, properly coated and sealed of course.

Interesting you say that as my half inch sheet seems every bit as rigid as comparable plywood and I have yet to see any temperature related expansion and contraction.