crack repair

Joined
Mar 11, 2010
Messages
23
So, I've browsed these pages since I joined and gained a ton of knowledge from them, so thank you. I have a 1985 Ebbtide Dynatrak that a previous owner had backed it into a post causing a bit of damage. I just want to make this water tight so I can get it in the water this season and over the winter I plan on doing a more extensive project.

Here is my current issue. This crack was a decent size crack so I cut out the portions of damaged glass and wood. Based on advice from one of the local marine repair shops, I used bondo glass as a filler and was planning on simply spraying some gel coat over it for this year. Unfortunately, the damage is directly above the bunk so all the vibration and weight of the boat hits it full force. I didn't necessarily trust the repair shops comments that this would be enough, so before gel coating it, I took the boat for a drive around some rough roads to test the strength. I, unfortunatly was proved correct and a small hairline crack reformed. So, I decided I need to glass over this to give it some strength. I sanded a portion around the damage (between 2-3 inches beyond the actual damage) through the paint to have glass to re-glass to. I hope that was needed and I didn't just ugly up my boat for no reason. :confused:

Anyways, my main question is how far should I extend the new glass to ensure proper strength. The picture below is just the transom side, but the bottom of the boat is an almost mirror image of this as far as how far I sanded out.

IMAG0019.jpg


I'm thinking about using a couple layers of woven roving and I'll float it in to hopefully not make the patch too obvious. Would CSM covered with mat be a better option? The damage really isn't that bad, but I extremely concerned about the location and how much vibration it will have to put up with so I want something strong.

Thanks for the help, and sorry for the book.
 

drewpster

Commander
Joined
Oct 17, 2006
Messages
2,059
Re: crack repair

The general rule of thumb is to grind out 12 times the thickness of the glass being repaired. In other words if the repair area is a panel 1/4 inch thick, you would multiply 1/4 x 12 = 3". So you would grind a taper surrounding the repair area 3" around it after removing all the damaged glass.
 
Joined
Mar 11, 2010
Messages
23
Re: crack repair

Ok, that's good to know.

Now that I have the size figured out, what kind of glass would be the best for this repair.

Do I need to re-enforce the bottom of the keel portion of this patch? I'm just thinking that when on the water, the force of the water will be working in direct resistence with the patch. If I just make sure to float (taper in your terms) the patch, will it be okay?

Thanks for the help.
 

Yacht Dr.

Vice Admiral
Joined
Feb 26, 2005
Messages
5,581
Re: crack repair

Hello Cowboy..

You should be fine using 1.5 oz mat. ( Mat is Great for bonding and has some structural value ).

However If you would like to put a few layers of 1708 It wouldnt hurt..

Sand prep gel buff afterwards..

YD.
 
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