Newby needs to repair hull

Hello, I just joined today, and need to repair my hull in 2 places on a 2000 maxum 2300 sr. I hit a very large rock doing 20 mph. Last check of depth gauge said 20 feet, then wham! It must have been lurking under 10 inches of water. I will try to put photos up if I can.
The first hole is in the front bottom of hull-I cut out the material and the hole is about 10 inches wide and 24 inches long. I am going to remove all bad fiberglass and chamfer to 12:1. I cannot access from the inside without removing the top half of boat, which also has the front section,dash, and floor molded in. I do not want to make access hatches either. I am thinking of doing all repairs from the bottom. I can clearly see into the hole to examine inside.
My thoughts where to place a backer laminate with a few strips of formica on the inside glued in place just to support the new repair while laying up. I was going to work from the outside inverted, since the boat weighs 4000lbs and I have no way of flipping it!
The original hull I would guess was fabricated with polyster resins and matting or a chop gun. There might be a layer or 2 of woven roving in there, but it looks to me that it was all matting, and the pieces pull apart easy (delaminated). The bottom is all black bottom paint, so I have no need to worry about gelcoating. I am simply going to put a new coat of bottom paint on.
I am going to use epoxy resin and a biaxial 1708 knytex cloth. I will need 12 layers to get to the 1/2 inch hull thickness needed.
I would appreciate all the information I can get to do this repair. I have done 2 transoms in the past, but that was 20 years ago, and I thought woven roving and chopped mat with polyster resin was the best route on them at the time.
I am wondering if I should vacuum bag, or if the epoxy is even thick enough to hold it inverted without vacuum bagging. Also, how many layers at a time should be installed?
I also have to repair the keel in the rear underneath the engine. I thought it was just a scrape, but it delaminated and popped the layer on the inside. The engine is out, and I will cut that section out (36 inches long by6 inches wide, and do the repair from the inside.
Thanks for any help.

 

need a fiberglass expert

ttttt

 

Can you get to the damage from the inside or is the tank in the way?

 

The ability to read and comprehend is not a godsend!

For me this was clear enough:

markd514

you are on the right road with your plan to start with.

The layup should hold without bagging when you use a epoxy resin with high thixotropy (thick stuff) for the first layers. Go for a layup schedule allowing to work on the green surface. Do not let the former layer fully cure before applying the next one. But do not try to work wet in wet, it will sag.

Regards
Richard

 

No ******* evidently you are ignorant on repairing as well as reading,I would suggest a 4th grade remedial reading comprehension then you could make better replies and defend yourself a little better,Now repairing a hull bottom should be done from both sides.

 

This is a common type of repair and it can be done from the outside. Your idea of a Formica backer is a good one and will keep your material costs down from less waste.

The first thing to do is jack the boat up and get it high enough to work under it securely, without fear it will fall on you. Then take a grinder to the damage area and feather the 'glass back several inches all around. This is after you've removed the obvious delaminated damage, which you can cut out with one of several tools. I use a reciprocating saw often on this task. Just hack it out, until you're back to good, solid laminate.

Feather the edges of the now widened hole, until it's at least half as thick (or more) along the edges. This will help tie the old laminate to the new laminate and prevent cracking out or concentrated stress risers between old and new.

Now your repair can begin with new material, which will bond to the hull shell. You have to decide which resin system to use, polyester, which is what you boat is made of or epoxy, which is a much better repair material for the back yard guy looking to fix the latest headache on his boat.

The next part is bulking in the materials with the resin system you've elected to employ. Try to make the laminate as thick, if not thicker then what was knocked out during the impact.

The mat portion of the Knytex you plan on using is only necessary for polyester, because of this resin's inherent weakness. Secondly the 1708 will suck up epoxy resin like crazy and isn't necessary, nor desired for epoxy. Use an all cloth layup.

 

It is better to do the repair from the inside for a couple reasons,One is the obvious as there is no fairing and some structure can be added to the repair,a vinlyester could be looked at as it can be gelcoated and match the factory bottom,with epoxy you do not have that alternative.

 

Well, yes you can gel coat over epoxy, though you will need a binder, though I wouldn't bother, I'd just paint to save the trouble. I agree it would be nice to have access at both sides of this for repair, especially for as War Whoop hints, you can employ some sort of mold for the exterior surfaces, greatly reducing fairing.

With careful setup and some experience, you could still do a reasonable job with a mold and working from the outside. The forward area look compound, but I suspect you could employ some 1/4" plywood, Plexiglas, even sheet metal to make a very close fitting female of the area. Of course, access to the other side to insure good contact would be quite beneficial, but on the other hand, you could make a layup that was sufficiently heavy enough to compensate for the lack of both side access. This isn't the way a pro likes to work, as it wastes materials and labor, but working under a shade tree, you can afford to kiss off a few layers of fabric and several ounces of resin.

 

Hey guy using formica is a very good idea or anything that is flexable i often use very thin plastic with packing tape on it or starboard and when you are getting ready to laminate overhead might i suggest mixing a little cabosil in the resin which will help keep the fabric in place and yes you will need a binder when spraying jell over Epoxy and i always use a Primer made by Duratec which comes in white and if you decide to paint the area that was repaired either way you will still have to use a primer.

 

You don´t get it, do you? Was the first statement about inside access not clear enough for you?

And VE in the hands of a complete novice? For a repair job? For whcih reason one would apply gelcoat on a boat repair in Ep?

Dude you better go building your high speed junks, and leave the advice on repairs to the experts like Paul Riccelli.

 

Thanks for all the information. This is a great forum.
(Hey, no fighting you two..lol) Both have valid points.

I have no access from the inside unless I cut a hole, which is counter productive. I wont be able to patch it nicely without covering it with carpeting.

 

"I have no access from the inside unless I cut a hole, which is counter productive." - The pros got that from the beginning and you are well on the right path. They also got that you do not care to gelcoat. You are doing fine.

 

Nuckle Head one always re-gelcoats a repair to restore the boat to as left factory condition and the VE is very user friendly even you could use some systems that come pre-promoted,

 

Newbe ,Doing a "Proper Job" requires work from both sides unless the damage is very minor.

 

True but myself it is easer to stay in the ester world sometimes also there are pictures of boats I have cut in half and restored and repairing nonskid is not a big deal.
sometimes the one sided repairs have a way of finding their way back,you and I have both worked for people who demanded the best possible work and nothing less ever left the shop.