Erik E

Replace Balsa J92

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Hi there folks,

 

I recently bought a J92 and I know that there are a few wet spots , so I am planning on replacing some Balsa in the Cabin. There have been previous topics on this I believe, but is it best to replace with Balsa or some other material. Light and strong is what I need.

 

Replace from the inside or outside???

 

Thanks in advance.

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As with all things, the answer is...wait for it..."It depends"

I'm generally a fan of using the same core material as originally built...makes everything easy from a panel stiffness, etc standpoint, as the properties of core material will be the same. The reality is, wet balsa core is really a result of poor maintenance, and a foam core would also be wet given the same level of maintenance.

If you are only doing small sections, and the deck looks good (i.e. not redoing the non skid, etc) and you have good access from below, then going at it from below is likely the right approach.  Requires more planning, from a brace your work in place, mix resins/fillers to correct consistencies to not get voids, as gravity is working against you.

If you are doing larger areas, and redoing the deck/non skid while at it, going in from above, where gravity is you friend is a bit easier for the first timer.

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Replace with balsa but keep the damn water out. Inside or outside repair depends on location and size. If it's a deck repair and small enough an inside repair avoids refinishing the deck. But grinding and glassing overhead really sucks. I worked on a J92 with soft spots around the port chainplate and genoa track. Both surveyor (with moisture meter) and I (sounding method) thought the repairs would be local so I started the repair below. Ended up ripping the balsa out from below all the way to the primary winch. Nasty job that should have been done from the top. The moral of this story is the only foolproof method of determining the size of the repair is to drill into the balsa from below until you find sound, dry balsa.

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Buy a decent moisture meter. I use the GRP 33, it is extremely consistent and does not lie.

https://www.jamestowndistributors.com/userportal/show_product.do?pid=4344&familyName=Wood+and+Composite+Moisture+Meter

36 minutes ago, Crash said:

As with all things, the answer is...wait for it..."It depends"

I'm generally a fan of using the same core material as originally built...makes everything easy from a panel stiffness, etc standpoint, as the properties of core material will be the same. The reality is, wet balsa core is really a result of poor maintenance, and a foam core would also be wet given the same level of maintenance.

If you are only doing small sections, and the deck looks good (i.e. not redoing the non skid, etc) and you have good access from below, then going at it from below is likely the right approach.  Requires more planning, from a brace your work in place, mix resins/fillers to correct consistencies to not get voids, as gravity is working against you.

If you are doing larger areas, and redoing the deck/non skid while at it, going in from above, where gravity is you friend is a bit easier for the first timer.

+100 

Ebay 92:

https://photos.app.goo.gl/9ALxB3V8auUkwakh6

 

92s wet core hull, meter indicated wet, survey said it was dry. The meter does not lie.

https://photos.app.goo.gl/rRt3oK8jrB4aUz3t6

 

 

 

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Vacuum bag new balsa in place.

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8 hours ago, Crash said:

As with all things, the answer is...wait for it..."It depends"

I'm generally a fan of using the same core material as originally built...makes everything easy from a panel stiffness, etc standpoint, as the properties of core material will be the same. The reality is, wet balsa core is really a result of poor maintenance, and a foam core would also be wet given the same level of maintenance.

If you are only doing small sections, and the deck looks good (i.e. not redoing the non skid, etc) and you have good access from below, then going at it from below is likely the right approach.  Requires more planning, from a brace your work in place, mix resins/fillers to correct consistencies to not get voids, as gravity is working against you.

If you are doing larger areas, and redoing the deck/non skid while at it, going in from above, where gravity is you friend is a bit easier for the first timer.

What modern foam cores absorb as much water as balsa?? I’m intrigued. 

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5 hours ago, mad said:

What modern foam cores absorb as much water as balsa?? I’m intrigued. 

Mad, you make a good point. None of the modern ones designed as core for boats...but that doesn't mean water can't or wont get into the laminate thru poor maintenance practices.  It just means the foam won't absorb the water, and so you won't eventually end up with rot, like you do with wet balsa. You can however still have delamination of skin and core.  Also, balsa core, properly isolated from thru deck penetrations, remains an easy to use, inexpensive core material, well suited to use by a DIY'r.  The original balsa core of my S2 9.1 lasted 35 years before it needed attention.  After I replaced the wet and or rotted stuff, and properly isolated all the thru deck penetrations, I'll bet that deck is good for at least another 35 years.  And it only went bad because no one ever bothered to rebed any of the deck hardware....

I was not, and am not,  trying to in any way say bad things about modern foam coring material....

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2 hours ago, Crash said:

Mad, you make a good point. None of the modern ones designed as core for boats...but that doesn't mean water can't or wont get into the laminate thru poor maintenance practices.  It just means the foam won't absorb the water, and so you won't eventually end up with rot, like you do with wet balsa. You can however still have delamination of skin and core.  Also, balsa core, properly isolated from thru deck penetrations, remains an easy to use, inexpensive core material, well suited to use by a DIY'r.  The original balsa core of my S2 9.1 lasted 35 years before it needed attention.  After I replaced the wet and or rotted stuff, and properly isolated all the thru deck penetrations, I'll bet that deck is good for at least another 35 years.  And it only went bad because no one ever bothered to rebed any of the deck hardware....

I was not, and am not,  trying to in any way say bad things about modern foam coring material....

Agreed, I just get bored of the many people going on about ‘wet foam core’ as if they’re experts here. Sure you can get delamination issues, the same as balsa, but it’s a lot better material than balsa and far more consistent. 

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I did the core around the chainplates on my 80. Replaced with corecell the next size/thickness down from the balsa. That allowed me to get it very close to the original thickness no bulging. Did it from the top 1.5’ by about 1’ sections. Then covered the whole deck in Kiwi grip. Looks good.

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I've replaced core on 3 different J's and the first response was correct, it all depends......

Real pain to repair a deck from the inside. But if a small area and nonskid is in good condition it is the better plan. Otherwise you will be doing Kiwi Grip or another type of nonskid to the entire boat. But if a larger area, it may actually be quicker to do from the outside even with the time to apply a nonskid. 

Also think about resale value. I would rather have a boat with the original nonskid as it will last a lot longer than any aftermarket product. But, I would also rather have a dry core with an aftermarket nonskid than a wet core.

If an area of wet hull, do that from the inside.

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On 8/14/2018 at 9:28 AM, mad said:

Agreed, I just get bored of the many people going on about ‘wet foam core’ as if they’re experts here. Sure you can get delamination issues, the same as balsa, but it’s a lot better material than balsa and far more consistent. 

Thanks guys. What would be a nice alternative for the Balsa and does it matter on the amount of replacement that is required.

 

Something else: how much weight are we actually talking about if a boat is wet ? are we talking about <50 kg or >50 kg?

 

 

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I like working on boats and do not mind these repairs. Also, I have only used balsa just to keep it consistent and it is easy to work with. 

Mad and others have a good point on the endless talk about wet core. Really, how big of an issue is it? My guess is that most J's over 20 years old have some wet core. The owners may not even be aware and it does not take away from the fun of sailing or racing. Weight is small is issue unless it is a massive area, at least in my limited experience. But most of my repairs have been around 1-2 sq feet that resulted from improperly bedded bolts through the deck.

I might have a different opinion on really large areas of wet core or if it were in a structural area with potential catastrophic failure. But on most older / smaller J's the cost of a professional repair could easily be more than the value of the boat. 

Yet these same boats go out all the time and you rarely hear of issues. Sometimes the best answer is to keep it from getting worse, monitor for changes and just enjoy the boat. 

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Just use balsa. If it gets wet again, it's going to be wet regardless of what's in there. Delamination is your real concern with moisture intrusion and balsa resists delam as good as, or better than, almost anything else out there.

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On 8/17/2018 at 7:51 AM, Erik E said:

Something else: how much weight are we actually talking about if a boat is wet ? are we talking about <50 kg or >50 kg?

  

 

It depends. Could be a little and could be a lot. Where are the soft spots? Sometimes water can get in and spread a bunch and sometimes only a little water gets in. Something you can do to cheat a little: let's say you are doing an area around a jib track. When you drill your holes to put the jib track back on, drill them oversize, tape the bottom and then fill the oversize hole with epoxy. Then go back and drill the proper sized hole through the middle of the epoxy. You have to be careful because the epoxy will be much more brittle than the original deck was so don't make the epoxy too big. Use large enough fender washers underneath and seal it up good. Even if it's around stuff like chainplates you can do the same thing. Much easier to do all that from the top. Working from below sucks. If you try to do it from below wear a tyvek suit with a hood and paper/plastic off everywhere. It'll only be a matter of time until you put your head/hair in it or walk through drips and track them all over the boat. Have you seen Dremel's mini circ saw? (link: https://www.dremel.com/en_US/products/-/show-product/tools/us40-ultra-saw) It's pretty cool and it has a height-adjustable base. The way the foot sits relative to the blade lets you (carefully) cut along convex surfaces. 

This is also a good time to take out a tape measure and make sure all of your deck fittings are even and symmetrical. Often you'll find that they are even/symmetrical to the deck but then the deck isn't square to the hull. Don't assume your keel is on straight either. 

edit: somehow I missed that this is a 92. Had it in my head that this was an 80. Doesn't change much other than your deck fittings and keel placement should be a little better than some of the 80's. 

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