Wet balsa core repair options?

[john61ct]

I would **never** rely on this type of technique to persuade me to take on even a "free" boat.

But if I'd spent years upfitting a beloved oldie, the condition reveals itself and I just couldn't justify a proper repair,

I'd consider such a solution to extend its useful-to-me life a few more years.

Maybe get lucky and it works great, lasts longer than I do!

But at some point most boats eventually get to the point, their time has come to get broken up.

[clockwork orange]

I havn't read all the posts but as a pro having done this many times I would always replace the core from the bottom if at all possible, yes its a bit more difficult working against gravity but with the majic of vacuum and a little thought its doable and you don't have to deal with the cosmetic issues of working from the top. Infortunatly it is not always possible due to molded liners etc but on older boats with fabric headliners etc its the way to go. Many boats were built with much too much of the laminate on the outside of the core and not much on the inside so you often damage the inside skin removing the old core so need to rebuild it before installing new core and then often the inner skin is not solid enough to install the core with weights without propping it up from the inside which you can't always do due to molded liners and on and on. Its usually much easier working from the inside against a much thicker outside skin, of course as I pointed out before its often not possible so you have to work from the outside but for me its always the second choice.

Steve.

[Terra Nova]

Originally Posted by Scout 30

...the more the core is rotten the more the foam can displace it. In fact, if the core is dry you have to add water to it...

Oh come on!

[Mike OReilly]

Originally Posted by Terra Nova

Oh come on!

Just following along here, but I think Scout is correct here TN. From Injectadeck’s instructions:

“… Lightly spray water if your dry rotted (Rare) and let set for 10 minutes. The more water it has the more solid the foam gets."

[Kelkara]

Originally Posted by clockwork orange

Infortunatly it is not always possible due to molded liners etc but on older boats with fabric headliners etc its the way to go.

Can I ask a dumb question ... What is a moulded liner? and how do I tell if I've got one?

[Terra Nova]

M--my point is Who would want to intentionally introduce water inside of a cored deck?!

[ramblinrod]

Originally Posted by Scout 30

How noble. 35 years of experience & you don't know that sensitization only happens when you come in contact with uncured epoxy.

1. The majority of 25+ year old balsa cored boats on the water, including crossing oceans, have moisture in the decks, so your belief that "no boat can safely have moisture in the deck, therefore it all must be removed", is clearly flawed.

2. Safe and reliable repairs have been completed with polyester resin since the development of polyester FRP boats, so your belief that "only epoxy resin can be used to repair boats" is clearly flawed.

I offer my customers repair options that I will stake my reputation and warranty on, and express the advantages and disadvantages of each, and let them choose which option best suits their needs. I feel that this IS doing them a favour vs incorrectly advising there is only "one way" to repair their boat.

I have never had a failure of any FRP repair I have ever made (1000s).

[Dymaxion]

Quick questions...
Has anyone used a rotary cutter tool like "Rotozip" to cut through laminate layer?

Has anyone tried a high pressure washer system for blasting out rotten core? I've seen the damage such a washer can do when held to close to a pine board and am thinking rotten balsa (and maybe good!) could be blown apart and the mulch flowed out via multiple drain holes. A small custom tip on flexible line that could be inserted beteeen laminate layers and poked/steered around.

I am surprised that the "ideal" hard setting high density foam doesn't exist yet. Here's hoping...

[Cheechako]

Originally Posted by Dymaxion

Quick questions...
Has anyone used a rotary cutter tool like "Rotozip" to cut through laminate layer?

Has anyone tried a high pressure washer system for blasting out rotten core? I've seen the damage such a washer can do when held to close to a pine board and am thinking rotten balsa (and maybe good!) could be blown apart and the mulch flowed out via multiple drain holes. A small custom tip on flexible line that could be inserted beteeen laminate layers and poked/steered around.

I am surprised that the "ideal" hard setting high density foam doesn't exist yet. Here's hoping...

I think the problem is the rotten core varies, some boats it looks normal, but wet. Others it's black and coming apart, but like most wood rot, there are still solid areas, so trying to blow it out of holes isnt really going to work.
I've often thought that maybe with a core that is wet, but not falling apart, could you hole saw a number of holes in a pattern from inside the boat, maybe 3" hole saw, and then dry it out with a vacuum and time... or heat/fan.... or enclosed AC for a week!? Once dry, inject with epoxy or whatever to make it sound again, and put the 3" plugs back in with epoxy slurry.

[ramblinrod]

Originally Posted by Cheechako

I think the problem is the rotten core varies, some boats it looks normal, but wet. Others it's black and coming apart, but like most wood rot, there are still solid areas, so trying to blow it out of holes isnt really going to work.
I've often thought that maybe with a core that is wet, but not falling apart, could you hole saw a number of holes in a pattern from inside the boat, maybe 3" hole saw, and then dry it out with a vacuum and time... or heat/fan.... or enclosed AC for a week!? Once dry, inject with epoxy or whatever to make it sound again, and put the 3" plugs back in with epoxy slurry.

To dry wet core without removing skin, one solution is to drill a pattern of small holes and hotvac the area.

[Cadence]

High pressure water? How much more does anyone want to saturate balsa that may not be bonded to the glass. High pressure air I can see although how do you know when your taking out rot or good balsa. I guess a little at a time and look at the waste.
Both seem like overkill.

[Scout 30]

Originally Posted by Dymaxion

Quick questions...
I am surprised that the "ideal" hard setting high density foam doesn't exist yet. Here's hoping...

Supposedly that's what Injectadeck is.

Here's another system that might dry the core without removal.

Hotvac Boat Hull Drying, Osmosis Treatment, Osmocure

[Cheechako]

Originally Posted by Dymaxion

Quick questions...
Has anyone used a rotary cutter tool like "Rotozip" to cut through laminate layer?

Has anyone tried a high pressure washer system for blasting out rotten core? I've seen the damage such a washer can do when held to close to a pine board and am thinking rotten balsa (and maybe good!) could be blown apart and the mulch flowed out via multiple drain holes. A small custom tip on flexible line that could be inserted beteeen laminate layers and poked/steered around.

I am surprised that the "ideal" hard setting high density foam doesn't exist yet. Here's hoping...

It isnt so much the hardness that's an issue, it needs to be closed cell foam which doesn't absorb much moisture. You can stand on regular styrofoam which is fairly soft and the PSI of your weight/area is likely higher than that on a deck.

[john61ct]

Originally Posted by Terra Nova

M--my point is Who would want to intentionally introduce water inside of a cored deck?!

Just like Gorilla Glue, hydrophilic formulas require moisture from H20 as a catalyst for the reaction.

Key word: lightly spray. Unrealistic perhaps when the board's not exposed.

And they did qualify that such "dry rot" is rare.

[Cadence]

Originally Posted by Cheechako

It isnt so much the hardness that's an issue, it needs to be closed cell foam which doesn't absorb much moisture. You can stand on regular styrofoam which is fairly soft and the PSI of your weight/area is likely higher than that on a deck.

Don't even mention Styrofoam in the same breath with polyester resin. I can not speak to epoxy. Maybe a little off subject but Styrofoam turns into a noxious vapor went exposed to polyester resin. FYI