hit pier and got a nice big crack in hull

[Woodonglass]

Uhh Huh pretty much!!! But...If the big patch fails they ALL come off!!!

 

[halltrail]

Ok, so Im thinking I may try to do the inside first. If I do that is it important to create that "dish" if I dont care about having a bump on the inside of the boat? Can I just rough it up and apply the layers? Hell, Ill apply a ton of layers if needed..lol...no one will see it in there...and I do have good access as well.

 

[jbcurt00]

Treat the inside as practice, even if it's mostly or completely hidden. Repair it the same as you intend to on the outside.

Then when you start on the exterior, you'll hopefully be just a bit better at the grinding, tapering, glassing, filling & fairing.

 

[halltrail]

Ok, Lets get too it then! Can I get some help on specifics. I need to order some 1708 fiberglass...is there a special thickness or kind? Suggestions for the resin and hardner that I need? I have angle grinders, dremal tool, die grinders. What should I use for grinding and I assume Ill need different grit sandpaper. Mixing cups? brush....Thanks fellas...Any help on what I need to get would be great.

 

[JASinIL2006]

Hi, 1708 is a specific thickness of cloth. It is a biaxial cloth that features 17 oz. double bias cloth stitched to 3/4 oz. CSM (chopped strand mat). The CSM (the '08' part) helps bind the cloth (the "17" part) to the work surface. Together, they form a really strong layup that's pretty easy to work with.

Generally, you buy the cloth in a particular width (38" and 50" are common) and you purchase it by the linear yard. For example, two yards of 50" 1708 would produce a sheet 50" wide by 72" long.

Does that help?

 

[Woodonglass]

Since the crack on the inside is at the junction of the transom and side of the hull it will be a bit more tricky. You will need to grind away the old glass and get down to fresh glass to ensure good adherance for the new glass. You'll need a Gallon of Standard Laminating Polyester Resin. I might bump it up to Vinylester resin. It's stronger and for this repair I think the best product to use. I think a Yard of 1708 will be enough and I'd also get a yard of 1.5 oz CSM (Choppped Strand Mat) too. Once your get the inside ground off you'll be able to see if the glass is fractured more than just what the crack shows. Make sure to grind back all fractured glass and make the patch large enuf to cover it. Dishing it helps build strength and remove any broken glass to ensure you bond to good solid glass. Pics of the inside AFTER you get it all ground down would be helpful. You never did post the distance from the transom to the main crack. To aid and ensure good adherance and strength my layup schedule for the repair on the inside once it all ground down and cleaned with acetone would be Duct Tape off the Outside Crack to stop bleed thru then..
lay a 2 " layer of CSM, 4" Layer of 1708, 6" CSM 8" 1708 and a final 12" layer of 1708. Outside layup, 2" CSM , 4" 1708, 4" CSM , 6" 1708, 9"1708, 12" CSM, 14" CSM.
The final Layers of CSM allow you to hide the Weave of the 1708 and give you a base for your Sanding and fairing material to make final blending easier. You can purchase an inexpensive PreVal Spray Paint system (under $10 bucks) @ Lowes to spray Gelcoat over the repair. As previously stated, Matching the Gelcoat to your existing will be a challenge. Wiping down the existing with Acetone and cleaning it really well is imperative. Once you do this then get a Gelcoat repair kit and begin the task of trying to match the color. Use toothpicks to dab small amounts of color into your base white color and then mix and use a hair dryer to dry it. Take notes to track your mix ratio. Once you're happy with the color mix up the color an spray on 3-4 coats. You want it thick. Use PVA, WAX, or cover the final Coat with plastic to block the air from it so it will totally cure.
I may have left out a few things but that should get you started. Keep posing pics and questions and we'll help you all along the process.

 

[Rickmerrill]

It really isn't that much more work to grind it to good glass but you can and should do it any way you see fit. There is plenty of fractured glass in there so yeah you'll end up with a hole by the time your done but that's no big deal. You'll want a marine grade laminating resin (does not harden in air) and some surfacing wax for the last layer of gelcoat so that it does harden. A lot of forum members order supplies from U S Composits, look at there 435 resin. That comes with the hardener but if you need to, figure enough MEKP to catalyze all your resin at 1.25% or so. I'd say a quart of gelcoat would cover the whole area and some tints if you want to try to color match.