bertram31.com

Guy's,
I am in the process of replacing the original 1961 1-1/4" cone valve thru-hull fittings in my31' express. I went with Groco 1-1/2" full flow ball valve thru-hull fittings with screened external pick-ups on each of the engine intakes. The original glass is 5/8" thick of solid laminate and is in perfect condition. They are located just aft of the engine box bulkhead between the 2 stringers. I also checked the thickness just under the starboard rub rail near the transom where the aft bilge pump discharge exits, also 5/8" of solid laminate. Another thru-hull just off of the port keel near the transom for my raw water/livewell intake is 1-3/4" thick.
With the cost of resin now-a-days there are very few boats made with the amount of glass that our old tanks were built with. They might be old but I'd rather have one, than some of the garbage that is being built now.

i couldnt agree with you more pete

No doubt, the early Bertrams were built with more glass than one would typically see today.

I have me B20 in a shop being painted and last time I was in there the glass guy who was grinding out some crazing mentioned that there was alot of glass, but commented that it was very resin rich.

I had never heard this before and never really taken much notice with the exception that fiberglass that I have put on the transom etc. seemed to grind differntly. Possible resin to glass content, possibly 1708 vs 24 oz roving and mat.

Anyhow, just curious if anyone else has thought that our beloved boats are resin rich?

Ian.

Pete
I have been working for a few years on DeNada and doing the same thing with Thru Hull fittings.

DeNada is 1966 Express.....my hull thicknesses are the same as you are reporting.

These boats built like tanks.......just love um! ! !

hb

Anyhow, just curious if anyone else has thought that our beloved boats are resin rich?

Without a doubt...

Before the advent of vacuum bagging, infusion, and SCRIMP techniques, along with a much more scientific approach to fiberglass composition used today, all fiberglass boats were resin rich.

A resin rich layup is almost unavoidable in small shop hand layup. Ideally, the resin to glass ratio should be 1:1

Lower resin to glass weight ratios produce a lighter, stronger, more flexible skin, where as higher resin to glass weight ratios produce a heavier, weaker, and stiffer skin.

All said though, the B31 and many other similar sized older boats, with their resin rich layups do just fine and have outlived many newer "high tech" high fiber to resin ratio boats.

And the higher the technology becomes the more inherent that problems can and do crop up.

Kinda' the same as comparing old steel cars of the '50s and '60s with their flathead engines to their new light weight cousins with computer controlled multifuel engines.

Simplicity usually out lives complexity...

Simplicity usually out lives complexity...

Amen! and how true that is and would be in alot of other area's also.

DQ

And what about the later iterations of the B31 hull? Is the hull thickness of my 1980 FBC any thinner or weaker than the earlier hulls ? Is it made of the same " old green fiberglass " ? I have heard it said they are lighter.Less weight to shove around but what about strength?

JR

Can't speak as if it is the same green glass, but remember, never a hull failure. Nothing to worry about. Still Bertram tough.