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Author Topic:   Stress Cracks

dowdhh posted 08-12-2010 09:02 PM ET (US)
I am getting stress cracks on inside top corners of transom [of a c.1960 13-foot presumably Boston Whaler boat with a 1996 Johnson 25-HP long-shaft on a Mini-Jacker plate]. I believe [the stress cracks] come from trailering and boating. I fill them [with WEST System resin] and they quickly return. Any ideas? Thanks
wezie posted 08-12-2010 09:30 PM ET (US)
Search "stress cracks" for a lot more info than you believe.
Basically, they are a surface crack in the gel coat that is an indication of a crack in the fiberglass beneath.
In order to "fix" them the structural problem must be addressed.
Filling the surface gel coat will not solve the problem.
Good Luck!
jimh posted 08-13-2010 09:24 AM ET (US)
Stress cracks occur when there is movement or stress in the laminate. With a heavy load on a 50-year-old boat's transom, you will have to add reinforcement to the laminate to prevent it from flexing and moving.
Tohsgib posted 08-13-2010 11:26 AM ET (US)
That is also a VERY common problem in older 13's and hence why they changed the transom. Personally I would think it is old age or that the engine is still not high enough and that is what is stressing it out. Some of those fixed mini jackers do not bring it up enough, only like 4". You can also use a transom saver while towing and see if that helps but I think they are kinda like snake oil.
contender posted 08-13-2010 12:52 PM ET (US)
I have also seen people connect the outer transom with the inner transom, using a long bolt/all-thread, or machined a part out of aluminum to connect the two transoms. Another way is to re-due the corners and make a fiberglass trust to the two transoms. Your boat is old and the fiberglass is good for about 25 years, it is just in need of some updating/repair...good luck
modenacart posted 08-13-2010 04:07 PM ET (US)
My Montauk has very thick gelcoat in those corners, which I am sure contributes to the cracking. I think it is difficult to spray correctly there.
Tom Hemphill posted 08-13-2010 05:35 PM ET (US)
A previous owner of my 1966 13-foot Sport installed two stainless steel threaded rods connecting the inner and outer transom. My subsequent surface repair of the gelcoat in the area you describe has held up quite well.
The guy I bought the boat speculated that the previous cable and pulley steering may have contributed to the stress cracks. Switching to Teleflex steering may have helped the situation with my boat.
dowdhh posted 08-13-2010 08:55 PM ET (US)
Thanks for all the input, I was thinking about the threaded rod approach,knowing others have done it is helpfull. It is also possible the motors not quite high enough,I'll look into that as well. I've completly redone this old boat,so those cracks really bother me. It has Teleflex steering,and the bracket is great! She gets up quick and wil reach 30mph with only me onboard. [Changes topic to begin a discussion about the website:]And she's definitly a whaler not presumably,(I didnt write that) so it seems these posts are edited.[Back to boating--jimh.] Any more ideas would be great. Thanks again!!
jimh posted 08-13-2010 10:18 PM ET (US)
ASIDE to dowdhh: for about 100 years in English publishing the use of square brackets denotes changes in a text added by the editor. Yes, I edited your article. The goal here is to collect and organize information, and it often becomes necessary to increase the information content by replacement of pronouns like "it" with the actual nominative or phrase that is intended.
dowdhh posted 08-14-2010 06:30 PM ET (US)
I've decided on a course of action for my stress crack problem. I removed the motor and bracket today. My plan is to repair the stress cracks then fill the transom notch using information from this web site. That should strengthen the transom reducing any flexing. I'll remount the motor and bracket about 1" higher. Hopefully that will do it. The thought of seeing threaded rods was unacceptable. Thanks everyone.
ASIDE to jimh my comment on editing was not criticism just an observation, I don't claim to be an expert on publishing (like you) I'm just a Whaler enthusiast who I believe, writes fairly well.
modenacart posted 08-15-2010 07:53 PM ET (US)
I am thinking of using the large engine washers to help take some of the load too. They should help keep the engine bolts from digging into the fiberglass on on the transom too.

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Author	Topic: Stress Cracks
dowdhh	posted 08-12-2010 09:02 PM ET (US) I am getting stress cracks on inside top corners of transom [of a c.1960 13-foot presumably Boston Whaler boat with a 1996 Johnson 25-HP long-shaft on a Mini-Jacker plate]. I believe [the stress cracks] come from trailering and boating. I fill them [with WEST System resin] and they quickly return. Any ideas? Thanks
wezie	posted 08-12-2010 09:30 PM ET (US) Search "stress cracks" for a lot more info than you believe. Basically, they are a surface crack in the gel coat that is an indication of a crack in the fiberglass beneath. In order to "fix" them the structural problem must be addressed. Filling the surface gel coat will not solve the problem. Good Luck!
jimh	posted 08-13-2010 09:24 AM ET (US) Stress cracks occur when there is movement or stress in the laminate. With a heavy load on a 50-year-old boat's transom, you will have to add reinforcement to the laminate to prevent it from flexing and moving.
Tohsgib	posted 08-13-2010 11:26 AM ET (US) That is also a VERY common problem in older 13's and hence why they changed the transom. Personally I would think it is old age or that the engine is still not high enough and that is what is stressing it out. Some of those fixed mini jackers do not bring it up enough, only like 4". You can also use a transom saver while towing and see if that helps but I think they are kinda like snake oil.
contender	posted 08-13-2010 12:52 PM ET (US) I have also seen people connect the outer transom with the inner transom, using a long bolt/all-thread, or machined a part out of aluminum to connect the two transoms. Another way is to re-due the corners and make a fiberglass trust to the two transoms. Your boat is old and the fiberglass is good for about 25 years, it is just in need of some updating/repair...good luck
modenacart	posted 08-13-2010 04:07 PM ET (US) My Montauk has very thick gelcoat in those corners, which I am sure contributes to the cracking. I think it is difficult to spray correctly there.
Tom Hemphill	posted 08-13-2010 05:35 PM ET (US) A previous owner of my 1966 13-foot Sport installed two stainless steel threaded rods connecting the inner and outer transom. My subsequent surface repair of the gelcoat in the area you describe has held up quite well. The guy I bought the boat speculated that the previous cable and pulley steering may have contributed to the stress cracks. Switching to Teleflex steering may have helped the situation with my boat.
dowdhh	posted 08-13-2010 08:55 PM ET (US) Thanks for all the input, I was thinking about the threaded rod approach,knowing others have done it is helpfull. It is also possible the motors not quite high enough,I'll look into that as well. I've completly redone this old boat,so those cracks really bother me. It has Teleflex steering,and the bracket is great! She gets up quick and wil reach 30mph with only me onboard. [Changes topic to begin a discussion about the website:]And she's definitly a whaler not presumably,(I didnt write that) so it seems these posts are edited.[Back to boating--jimh.] Any more ideas would be great. Thanks again!!
jimh	posted 08-13-2010 10:18 PM ET (US) ASIDE to dowdhh: for about 100 years in English publishing the use of square brackets denotes changes in a text added by the editor. Yes, I edited your article. The goal here is to collect and organize information, and it often becomes necessary to increase the information content by replacement of pronouns like "it" with the actual nominative or phrase that is intended.
dowdhh	posted 08-14-2010 06:30 PM ET (US) I've decided on a course of action for my stress crack problem. I removed the motor and bracket today. My plan is to repair the stress cracks then fill the transom notch using information from this web site. That should strengthen the transom reducing any flexing. I'll remount the motor and bracket about 1" higher. Hopefully that will do it. The thought of seeing threaded rods was unacceptable. Thanks everyone. ASIDE to jimh my comment on editing was not criticism just an observation, I don't claim to be an expert on publishing (like you) I'm just a Whaler enthusiast who I believe, writes fairly well.
modenacart	posted 08-15-2010 07:53 PM ET (US) I am thinking of using the large engine washers to help take some of the load too. They should help keep the engine bolts from digging into the fiberglass on on the transom too.