Cut Through The Bottom Of Boat Removing Floor PLS Help

[Daniel77]

I recently purchased a 17ft deep V fiberglass boat that required a new floor and transom. Stringers are still solid and dry.
Whilst cutting our the floor around the stern i went a little to deep and cut through the bottom of the hull both on both port and starboard sides
the cut is about 14 inches long on both sides about 3" in from the side of the boat.
My question is would it be acceptable to perform a repair from the inside of the boat only as i have been reading that a structural repair should be done from both sides. Im not to sure about fiber-glassing upside down. I have been kicking myself for weeks over cutting through the bottom and cant decide how to best fix this mistake. Your help would be greatly appreciated.

Thanks in advance.

 

[tpenfield]

It happens. . .

If you do not fix it from the outside as well, the cut will continue to grow with the flexing of the hull. My recommendation is to sand the outside area and apply some biaxial cloth to the outside first. Cover the area with a piece of plastic drop cloth while it is curing so that it will be reasonably smooth.

Then fill the cut from the inside with some 'peanut butter' mix and then top it off with a similar piece of biaxial cloth as you did on the outside.

Maybe post some pictures of the cuts for further comment.

 

[Daniel77]

Thanks tpenfield. Would you think best to grind a V into the bottom to repair. Would stop drilling the end of each cut be an option to stop the cut growing? I will post a pic shortly. Thanks again

 

[Scott Danforth]

you want to feather the repair from both sides. Woodonglass has a graphic somewhere to show this simple repair.

 

[82rude]

Dont be afraid to glass upside down its, no big deal.

 

[fhhuber]

For each 1/4 inch of fiberglass thickness, feather out 1 inch inside and outside kind of like you are making the cut into a knife blade. At the cut it should be as thin as you dare. Credit card thin is thicker than you want.
You'll end up with a REALLY wide patch area.

Then lay in multiple layers of cloth and mat. Maybe just one thick mat on the inside, because you don't really care if that turns into a bulge, but the outside I'd do 5 oz cloth layers (alternating weave direction by 45 deg each layer) for main thickness building followed by 2 oz with each layer getting wider. the idea being to end up filling JUST a little less than full thickness including gel coat all the way across.
Sand that smooth then finish with gel coat.

Your boat's gel coat might be 1/16 inch thick or more... The patch's gel coat should be almost as thick. You have to allow for that when laying in the fiberglass cloth then sanding.

With good color matching of the gel coat the patch will be difficult to impossible to find from the outside.

The patch will be bonded so cloth bridges the cut inside and out, making it very strong. If you just feather on the inside (easier to make it look good on the outside.... you think) then the edges of the cut might lift from the patch and break through your gel coat.

 

[Chris1956]

Gee, I would use 2 layers of heavy roving plus poly resin on the inside and overlap the cut an inch or more on each side and each end. Putty the cut from the outside to fill it. Then grind the outside down into an oval-shaped void and lay a few layers of cloth (increasing in size, small pieces first) to fill the void. You can putty the outside to better feather it, or use gelcoat.

The heavy roving is the structural fix and the cloth is the aesthetic fix. It should be stronger than the original, by a significant amount.

 

[gm280]

Daniel77, I hope you understand that there are many many iboaters that have cut through their hulls when refurbishing them. It is almost a guarantee to do that. But with fiberglass, it is not a big issue. You can fit it and make it look like it never happened. But you have to fix it from both side to make it work properly. The more you fiberglass, the better and easier you will get at it. JMHO

 

[Daniel77]

No Title

Hi All, Thanks very much for the advise, this is actually the third basket case boat that i have purchased as a restoration project. I keep telling myself never again but keep finding myself wanting to do another one. Its become an addiction. The best part of this project is that i still have my last restoration project finished so i still have a boat to use while i restore this one. Although with the fist two i never cut through the floor.

See the $500.00 AUD barn find below. It has been sitting in a storage shed for 22 years untouched. I had to pump the tires up to move it. The old blue band 80hp mercury was a challenge as i had to replace fuel lines and just about every electrical cable crumbled away while trying to route the new fuel lines through. It now runs well but i have purchased a more modern (1998) 75hp low hour Suzuki to replace the (1980) Merc 80hp.

Appreciate the help and thanks again.

 

[Woodonglass]

with the advent of Biax Fabric the use of Heavy woven roving is seldom needed. When Building for bulk it's ok but for a simple hull cut. Two layers of 1708 biax on the inside and then 2-3 layers of 1.5oz CSM on the outside will yield a great repair. For small patches like this you can also use a PreVal spray system to apply the several coats of Gelcoat. The Color matching is normally the big issue since Old gel will fade faster than new. Even if you get it perfect at first, the next season you'll see the patch. On the bottom of the hull who cares!!!

 

[Daniel77]

Hi Woodonglass, I purchased a 110 pound roll of Stitched Biaxial 0?/90? 1135g/m2 for the floor and transom + 100 meter roll Woven Roving Tape Plain 830g/m2 @ 6" wide. [FONT=Helvetica, Arial, sans-serif]I also want to add another layer to the existing stringers & boat hull as the boat is 43 years old i thought it might benefit from a little extra strength. in hind sight the materials i have purchased may be a little to heavy to work with as i was thinking that i would only be working on flat surfaces. Would CSM offer any strength for such a repair on the outside? i do have some small amounts of lighter woven to work with on the outside, i just want to ensure that i do the best repair possible as the boat will be used in rough sea waters and this sort of thing will drive me nuts if i feel the repair is inadequate. The repair on the bottom doesn't have to be perfect as no one will ever see it on the bottom. [/FONT]

 

[Old Ironmaker]

I have nothing to add because I have never worked with fibreglass. What I do want to say is I feel your pain and have total empathy for you. I have done some silly things at home that I kicked myself for a very long time. Luckily not on the job. Don't sweat it, as we say around here stuff happens. Getting down on ones self yields no positive results. Now "get er done".

 

[ezmobee]

Dont be afraid to glass upside down its, no big deal.

With him being in Australia isn't all his fiberglassing upside down? :laugh:

 

[Daniel77]

Fiberglass work down under is one thing but fiberglass work upside down is another. Last i looked we were standing the same way up. ☺☺

 

[gm280]

Daniel77, Before tackling the bottom section, do some fiberglass on the top side first and get some feel for how it works and kicks. Then you can go to the bottom side to work. The learning curve is really quick. So you will easily get the hang of it instantly. JMHO