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Author Topic:   Repair of Cracks

flboy0638 posted 11-25-2010 03:34 PM ET (US)
I am restoring my1982 Newport Boston Whaler. Today I dremeled or v'ed out the cracks in the gelcoat where stancions, cleats, and other hardware sat. Did I do it correctly? Make any suggestions you see fit. I think you can see from the pic what I did, what the crack looks like before I vee'ed out, the size compared to a penny, and what I used in my drill to do it. Bow rails are NOT going back on. Let me know how to improve if I need to:
http://s1208.photobucket.com/albums/cc374/flboy0638/Nov_25_2010/?action=view¤t=stancion_cracks2.jpg
Blackduck posted 11-26-2010 12:49 PM ET (US)
The only problem is that they will crack again. I would leave tight checks like these alone. New gel coat does not bond that well to old, and expansion and contraction will cause most of this type of repair to fail. Cracks like these do no harm, and nobody sees them but you.
flboy0638 posted 11-26-2010 12:54 PM ET (US)
Thats exactly why I have posted here. I thought I was doing a little overkill work.
So, just gelcoat right over these right?
Blackduck posted 11-26-2010 01:12 PM ET (US)
You can't just go over cracks like these, the will come right back. You need to remove all the old gel coat. I thought you were just making some cosmetic repairs.
flboy0638 posted 11-30-2010 06:18 PM ET (US)
The way it was explained to me is just just had to sanded real well, remove all imperfections, vee-out the spiker cracks
Blackduck--Ya got me worried partner. I am not complaining though. Thanks for any input you have.
You saying I got to sand all the gelcoat off the boat?
Blackduck posted 12-01-2010 04:28 PM ET (US)
If you don't remove a gel coat crack, and just cover it with more gel coat, it is very likely that its will return. If you sand them down to the laminate, you have a much better chance of a finished product that will remain crack free for years to come. You don't have to sand the entire boat down to nothing, just the cracked sections.
jimh posted 12-02-2010 09:25 AM ET (US)
[Redacted this discussion to focus on repair of cracks. For discussion in REPAIRS/MODS please keep each thread on a single topic of repair.--jimh]
jimh posted 12-02-2010 09:29 AM ET (US)
Cracks in gel coat typically occur from stress due to flexing or movement of the laminate. To prevent cracks from reoccurring, you have to stabilize the laminate and remove the stress point. This may mean adding some strength to the laminate to prevent flexing. Success is not automatic, as it may not be possible to remove flexing from some areas due to the original design.
Cracks in gel coat can also occur from poor maintenance and exposure to sun. Cracks of this type are not caused from underlying movement or stress, but from shrinkage of the gel coat due to excessive heat, sun, and drying.
flboy0638 posted 12-06-2010 09:05 PM ET (US)
Just to reiterate a little:
=====Why am I repairing the small cracks?
Because the stantions are coming off and there is already screw holes there.
=====Why not reinforce the laminate?
Because in my opinion the are stress cracks from the hardware
that was tightened down.
=====What did I gleam from this thread?
That where there is a crack, sand down to laminate to do correctly. You do not have to sand all the gelcoat off a boat
in preparation for painting/gelcoating.
jimh posted 12-06-2010 09:10 PM ET (US)
If the cracks radiate from the fastener hole, they are just the result of sloppy workmanship in the initial assembly of the boat. It is quite common to see on Boston Whalers that the gel coat layer surrounding a screw fastener is cracked, particularly if the hole is hidden by some overlaying component. Cracks like this are the result of forcing the screw fastener through the gel coat layer via a hole that was too small. They are very common on Boston Whaler boats. At the factory the assembly was not done with care. But, since in most cases these holes were covered up, they are not seen and are not a cosmetic problem.
When you use a screw fastener you must relieve the hole in the gel coat layer to a diameter that is larger than the screw. If you do not, the gel coat layer will fracture.

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Author	Topic: Repair of Cracks
flboy0638	posted 11-25-2010 03:34 PM ET (US) I am restoring my1982 Newport Boston Whaler. Today I dremeled or v'ed out the cracks in the gelcoat where stancions, cleats, and other hardware sat. Did I do it correctly? Make any suggestions you see fit. I think you can see from the pic what I did, what the crack looks like before I vee'ed out, the size compared to a penny, and what I used in my drill to do it. Bow rails are NOT going back on. Let me know how to improve if I need to: http://s1208.photobucket.com/albums/cc374/flboy0638/Nov_25_2010/?action=view¤t=stancion_cracks2.jpg
Blackduck	posted 11-26-2010 12:49 PM ET (US) The only problem is that they will crack again. I would leave tight checks like these alone. New gel coat does not bond that well to old, and expansion and contraction will cause most of this type of repair to fail. Cracks like these do no harm, and nobody sees them but you.
flboy0638	posted 11-26-2010 12:54 PM ET (US) Thats exactly why I have posted here. I thought I was doing a little overkill work. So, just gelcoat right over these right?
Blackduck	posted 11-26-2010 01:12 PM ET (US) You can't just go over cracks like these, the will come right back. You need to remove all the old gel coat. I thought you were just making some cosmetic repairs.
flboy0638	posted 11-30-2010 06:18 PM ET (US) The way it was explained to me is just just had to sanded real well, remove all imperfections, vee-out the spiker cracks Blackduck--Ya got me worried partner. I am not complaining though. Thanks for any input you have. You saying I got to sand all the gelcoat off the boat?
Blackduck	posted 12-01-2010 04:28 PM ET (US) If you don't remove a gel coat crack, and just cover it with more gel coat, it is very likely that its will return. If you sand them down to the laminate, you have a much better chance of a finished product that will remain crack free for years to come. You don't have to sand the entire boat down to nothing, just the cracked sections.
jimh	posted 12-02-2010 09:25 AM ET (US) [Redacted this discussion to focus on repair of cracks. For discussion in REPAIRS/MODS please keep each thread on a single topic of repair.--jimh]
jimh	posted 12-02-2010 09:29 AM ET (US) Cracks in gel coat typically occur from stress due to flexing or movement of the laminate. To prevent cracks from reoccurring, you have to stabilize the laminate and remove the stress point. This may mean adding some strength to the laminate to prevent flexing. Success is not automatic, as it may not be possible to remove flexing from some areas due to the original design. Cracks in gel coat can also occur from poor maintenance and exposure to sun. Cracks of this type are not caused from underlying movement or stress, but from shrinkage of the gel coat due to excessive heat, sun, and drying.
flboy0638	posted 12-06-2010 09:05 PM ET (US) Just to reiterate a little: =====Why am I repairing the small cracks? Because the stantions are coming off and there is already screw holes there. =====Why not reinforce the laminate? Because in my opinion the are stress cracks from the hardware that was tightened down. =====What did I gleam from this thread? That where there is a crack, sand down to laminate to do correctly. You do not have to sand all the gelcoat off a boat in preparation for painting/gelcoating.
jimh	posted 12-06-2010 09:10 PM ET (US) If the cracks radiate from the fastener hole, they are just the result of sloppy workmanship in the initial assembly of the boat. It is quite common to see on Boston Whalers that the gel coat layer surrounding a screw fastener is cracked, particularly if the hole is hidden by some overlaying component. Cracks like this are the result of forcing the screw fastener through the gel coat layer via a hole that was too small. They are very common on Boston Whaler boats. At the factory the assembly was not done with care. But, since in most cases these holes were covered up, they are not seen and are not a cosmetic problem. When you use a screw fastener you must relieve the hole in the gel coat layer to a diameter that is larger than the screw. If you do not, the gel coat layer will fracture.