Advice on a project boat part 2 (stress cracking)?

Question

Thank you everyone who has answered. Has been a big help!

http://www.vintageibm.net/boat

I did check the transom by moving the motor up and down. The transom flex’s a little bit I would call it normal for an almost 1 in think piece of plywood! With I would guess an 100 pound motor on it!

Just how bad is stress cracking on a fiberglass boat? My Boat is an early early 60’s and has some stress cracking pretty much scatter all over/around the boat here and there ( on the outside/Hull or body)! The biggest areas are around the motor mounts (transom) and quite few around the bottom of the boat (Were the hull meets at the bottom, runs the length of the boat the bottom of the “V” I guess that’s called the keel? That has stress cracking some are bigger you might be able to fit a piece of thin paper in the bigger ones! Smaller ones are just hairline! They run ever which way up down side to side!

Is that a big deal Or? Can I just sand paint and refinish and that will take care of it

Answer 1

dont stress over it

Answer 2

Most times  stress cracks come from the motor torque and the pressure of the motor on the transom during transportation and rough water, Personally I would check the condition of the transom from the inside, take a Philips s***w driver and poke around the transom in many different areas, be care-full not to puncture the fiberglass, you will feel either a solid transom or sponginess. if you find any sponginess regardless of its location then the inner transom wood needs to be replaced,

Answer 3

the bigger ones you described could become an issue in bad weather.... why not just glass over them or at least fill them in with resin

Answer 4

I'm with George here. Stress cracks in the gelcoat are often unavoidable signs of age and UV damage. Frequently, unrealistically stressed-out joins that are part of the design will cause this- blame the architect, not the manufacturer. Fiberglass will bend and give as it ages- if the bending is visible in a join or on a part of the hull that requires strength (most of the hull!), you need to go down to bare fiberglass and see if the cracking extends into the fiberglass itself- it could be that the gelcoat is being flexed loose, and that will happen with older boats. If the glass of the hull has extensive cracking under the gelcoat, you can either cut out and replace that section of the hull, or you can put a skin coat of fiberglass mat over the cracked area, so long as you reinforce that entire section of the hull. Reinforcing the hull requires that you give some additional structure and shape to the hull if it's in a flat section of the bilge- s***w down well-smoothed 1X1 wooden strips and glass 'em over.

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