Major Core Damage, Repair Ideas Neeeded

WoundUpMarine

Captain
Lite User
Joined
Jan 1, 2012
Posts
4,143
Likes
2,320
Location
Boothbay, Maine
Boat Make
26 Duffy, 14 Holland

Seanair

Member
Joined
May 17, 2013
Posts
29
Likes
26
Location
Rhode Island
I have done both, and from my experience attempting it from below is far more arduous than from the top. At the end of the day epoxy is more liquid than solid no matter how much you thicken it and the amount that drips down is very difficult to minimize and contain. Plus your faced with clamping or propping it up until it cures which is much harder than weighing it down from above.

I would cut a small area out from the top, say 6" x 6" just to get a sense of what it looks like. A water meter would help as well to map the area; often its not as wide spread as you think (learned this the hard way).
 

Lion's Paw

Senior Member
Joined
Mar 31, 2012
Posts
161
Likes
45
Location
Frisco, NC
Website
www.divehatteras.com
Boat Make
42 Duffy
I recored the majority of the decks and house on my duffy last year, its all coosa board and epoxy now.
Gravity is not your friend if you try this from underneath, but it is if done from above. You may have to support the inner skin from below if it is as floppy as it appears in your pics. Fairly simply with some wood propped up against it from below.

You may find it is not as extensive as it appears so spot repair may be possible. Taking the time to investigate the extent of the delaminated areas is worthwhile. However at some point it becomes easier to just rip all the bad core and deck off and glue it all back together with new materials.
 

Toolate

Captain
Lite User
Joined
Aug 6, 2013
Posts
6,096
Likes
2,006
Location
Southwestern CT
Boat Make
1998 36' Sabre Express CAT 3116TA's, 2015 ROS Scotia 16 Etec 50

Jjammer

Senior Member
Joined
Aug 12, 2019
Posts
236
Likes
96
Location
Newbury, MA / Camden, ME
Boat Make
36 Stanley / John Williams
Cut off top skin, remove wet core but preserve bottom glass skin if it’s in decent shape (if there is a bottom skin looks like there is)...new layer of glass on bottom skin then bed new core of choice with a cabosil/resin slurry. New glass over core and let the fairing begin.
 

Kenneth

Senior Member
Joined
Jun 19, 2014
Posts
160
Likes
49
I done a 26 foot boat but i was able to get the top cap off the boat and turned it upside down, cut and ground to bare glass and re cored it. Lots of work either way you go.
 

Keelboater

Captain
Joined
Oct 3, 2013
Posts
5,546
Likes
3,513
Location
Clinton Harbor
Boat Make
35' Bruno & Stillman
" The edges were never sealed "

Was this a home built kit boat or just another day at the builder's shop? I'm thinking that working from the top would cut the profanity down to 1/4 of what would easily fly if you opted to work from the bottom.
 

Bill

Administrator
Joined
Aug 30, 2011
Posts
3,543
Likes
2,594
Location
Hull, Ma
Boat Make
27 Terry Jason
John it’s gonna be a pain either way. Do you have pics of the top? If you do it from the top you are gonna have to cut along the very edge or close to it if the core extends out to the toe rail. to get the core all the way out and not leave a void and then have to get remainer out with a oscillating tool. Then when you go to glass it you aren’t gonna have much room over overlapping the glass. Idk but maybe zip it out from the bottom with a roto zip saw then grid down the top layer from under and glass a piece of chop strand up there then trowel core bond and hammer that core from the underside with a roofing roller let that kick Then 2 layers of 1708 I think.. sucks either way just an option

60DFED37-B627-451B-9B97-893977B70645.png
 

Brooksie

Captain
Joined
Mar 25, 2013
Posts
1,377
Likes
512
Location
Cape Cod
Boat Make
Bruno-Stillman 35
I have repaired several areas of my deck and trunk cabin over a period of years by drilling and injecting from the bottom but nothing larger than 3' x 3' or so at a time. However I see no reason why larger areas could not be done by the same method which I have described here a couple of times. I would think that no matter how you opt to do the foredeck, injecting would be the best method for the side decks.
You don't mention the size of the boat?
 

sockeye

Senior Member
Lite User
Joined
Nov 18, 2011
Posts
144
Likes
62

scout 30

Member
Joined
May 14, 2015
Posts
52
Likes
15
Location
Florida
Boat Make
Tashmoo 18, Scout 30, Bauer 10
While it’s appealing in principal I’m leery of any injection approach being a long-term solution.
Can't blame you there but high strength structural foam is a viable core material. Certainly makes more sense that injecting epoxy into a wet core. Unlike epoxy, which will not stick to anything wet, this stuff uses moisture as a catalyst. I don't know if you've ever done this kind of repair before but I have, from below, & it truly sucks! I hope this stuff works because if it does it would be a godsend.
 

Yesac13

Senior Member
Joined
Mar 15, 2018
Posts
233
Likes
105
Age
39
Just had an idea. It may not be workable, tho but mentioning it anyway.

Cutout the rotten core from underneath. Remove any traces of the core.

Then lay down 1-3 layers of fiberglass on one side of a coosa (or whatever) board cut to shape. Let it cure. Then slather epoxy or whatever on top of that coosa board with no fiberglass on it... press it upwards. Leave it there with supports holding it up. When it cures, tape fiberglass over any seams.

Downside of this method is that the deck shape may be distorted if the top fiberglass is super thin. Upside is not much fiberglassing upside down because already done before this step. Only mess is the fiberglass tape over the seams but that is a smaller project. Do take care to cover the floors of the boat with plastic to catch any epoxy drips. You can lay fiberglass tape then put plywood covered with plastic to hold it up while it cures. Then when it's cured, sand and paint/gelcoat.

The possible deck distortion is the biggest potential problem I can think of. Perhaps create a template and weight it down on the deck top... that way pressing the core replacement underneath doesn't distort the deck itself. Maybe possible to create a mold to match the deck camber? A bit tricky...

Working from above is easiest of all but requires lots of cosmetic work which may not be desirable if the original gelcoat is still in good shape.
 
Last edited:

Jjammer

Senior Member
Joined
Aug 12, 2019
Posts
236
Likes
96
Location
Newbury, MA / Camden, ME
Boat Make
36 Stanley / John Williams
Can't blame you there but high strength structural foam is a viable core material. Certainly makes more sense that injecting epoxy into a wet core. Unlike epoxy, which will not stick to anything wet, this stuff uses moisture as a catalyst. I don't know if you've ever done this kind of repair before but I have, from below, & it truly sucks! I hope this stuff works because if it does it would be a godsend.
I’ve done upside down work it does suck for sure.

I’m doubting the stuff works long term....also distributing the foam throughout the entire core while the existing core is still present is near impossible without hundreds of holes. At that point just cut off the top skin.
 

Brooksie

Captain
Joined
Mar 25, 2013
Posts
1,377
Likes
512
Location
Cape Cod
Boat Make
Bruno-Stillman 35
Too bad you are not nearby me. You would be welcome to come by and I would show you repaired areas, some done 20 years ago, that are solid as concrete and done from below by injecting.
 
Top Bottom