Wet Stringers and balsa core

Does anyone have any experience with a system called DRYBOAT? I was talking to a surveyor who said it has been around for a while and it can be an alternative to cutting out and replacing for wet balsa coring and stringers

no experience...but worth pursuing...new tech like this may be the answer for old tech problems...

skeptics included....I would wait before I spent a lot of money on some process like this...but after one or two successful jobs the result should be pretty evident in short order....just have to research and follow-up.

Plus one above, and please report your findings. We can use a good product for our aging decks.

Thanks for the feedback. I talked to a couple of people who had wet stringers, sides and bottoms and they sounded pretty happy with the results(and price, compared to other estimates they got). And the surveyor says it has been successful for quite a few years now and it is not only an economical alternative, but he also liked that it was a fraction of the impact that is made when you cut out and replace. And on stringers(as long as the form has not collapsed), they leave the engines in, so cost is much less.

Looks promising but with only two locations I hope your close. Something I could use as I have some wet decks (areas) but wouldn't want to pay for their hotel, flight, transportation cost, etc to begin work.

Here is what I found out so far and shared on other sites:

I have been asking because my main issue is wet stringers in my 1992 Cruisers Esprit. AND I did confirm that this is NOT a vacuum ("hot vac") type product. It is dry (< 2% RH), warm air being introduced into the problem areas at about 2 PSI. Not a dehumidifier, but they are somehow taking the moisture out of the ambient air. No peeling, works on any irregular surface, such as stringers, bulkheads, etc. On stringers the engines, generators, etc stay in the boat when they dry them out. On wet coring, they can go after it from the inside(not always, but that is there first choice) so it doesn't even impact the gel coat. I was given references on stringer jobs they have done.

OK, so here is the interesting thing I was told today by a design engineer at a major boat builder:
There are times stringers can be rotted out completely and it will not affect the strength or integrity on some boats at all, in fact it could be the opposite.

It all depends on how the wood is used. If the wood is only used as a form to wrap the glass around, and the layers of fiberglass (and how they attach/bond to the hull itself) are designed to be the strength, then, from a structural strength standpoint, anything that interrupts how all the layers were laid in and (how they all bond together in the original layup done in the mold) can weaken the engineered design. He compared it to uni-body construction in our cars. He did however say that if the fiberglass has actually cracked and/or collapsed, that is another issue.
And I think he was being sarcastic when he said "and of course anytime they survey wet, then wet stringers are definitely a problem"

Oh, and it is portable, in a trailer and comes to the boat.....

psneeld said:

no experience...but worth pursuing...new tech like this may be the answer for old tech problems...

skeptics included....I would wait before I spent a lot of money on some process like this...but after one or two successful jobs the result should be pretty evident in short order....just have to research and follow-up.

Click to expand...

So, as suggested, I did the research and here is my follow-up:
Posted this question on other forums and ended up using system on my stringers. For those interested, this recent thread on THT is pretty informative:

Looking for Pursuit Boat owners with balsa core damage from water infiltration. - Page 5 - The Hull Truth - Boating and Fishing Forum

Thanks for sharing that info, cruisers. The process used seems like a more reasonable approach to wet core anywhere. There's at least one guy on the FL east coast that replaced a full hull peal and glass system with holing the hull and then deluging daily with fresh water rinses and applications of huge amounts of alcohol. The process cost under 10K vs. a full peal, dry-out and glass for about 22 to 25K. If we're going to evolve at all in the hull repair methodologies, it's probably going to require a few unorthodox investments......something that few yards have the motivation to undertake.

I was involved in the sale of an 80 foot motor yacht a few years ago and we found high moistures readings in the core. However the core was foam not balsa. Dryboat was contracted to dry the core and their dryers were on for almost two months. A marine surveyor oversaw the project and the moisture readings showed a big improvement. There were two areas on the hull that we cut out and a new core put in.
I talked to a few other surveyors while the project was going on and there was a strong difference in opinion as to the effectiveness.
Since this was a large offshore yacht that had already done trips from California to Hawaii and also a Trans Atlantic crossing the expense of yard time on the hard plus other bottom work that was done was worthwhile. When the boat was splashed again the surveyor said the hull should be good for another 30 years.

Dryboat trailer was in our warm storage building over the winter doing their thing to a early 90's 63' Sea Ray. Bottom and transom were full of tubes to dry them. Took about 3 months but owner was vry satisfied with the results.

yachtbrokerguy said:

I When the boat was splashed again the surveyor said the hull should be good for another 30 years.

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This sounds like of one of the surveyors I talked to before going this route. This spring he was involved in the sale of a very large, older (1972) Viking. He discovered intrusion in the stringers, bulkheads, deck areas and transom. He said his experience with Dryboat goes back 7 years and he has referred them on a number of occasions. According to him, if this system had not been used, the owner probably would have scrapped the boat as the estimates to repair would not have made sense economically. His comment was "that would have been a shame, because it is a beautiful vessel, with a ton of character and mechanically very well maintained". He said the hull was given a "25 year extension".

I have included a pic of my boatdeck in an area that had 2 x 8 ga screws holding down a stauchion support. It took 30 years to get to this stage. The black area is rotted, and best removed. The blond exposed area was wet, so it was removed as well. The grey area is the fiberglass deck surface painted with a nonslip finish

Hammer tests indicated soft spots. Then the extent of the wet area was outlined by drilling small holes in the top glass layer then further into the core, rather than using a moisture meter. The small drill holes are easily repaired as part of the deck re-finishing. Rotten core was obvious, but we kept going outwards from that until the balsa was dry. Had we been able to dry the blond coloured wet areas then the repair area would have been substantially reduced, so I think using the Dryboat process prior to cutting out the rotten core would have a lot of merit.

cruisers5357 said:

So, as suggested, I did the research and here is my follow-up:
Posted this question on other forums and ended up using system on my stringers. For those interested, this recent thread on THT is pretty informative:

Looking for Pursuit Boat owners with balsa core damage from water infiltration. - Page 5 - The Hull Truth - Boating and Fishing Forum

Click to expand...

I really appreciate this post, as I learned a lot by following your links. It certainly changed my opinion of several manufacturers who I'd previously thought were quality builders. In my over 40 years of messing about with boats I've always been amazed how some boats are considered high quality, despite being nothing but a pile of latent defects, and others considered low quality, yet have none of those issues. I eventually realized people were confusing their purchase price with the definition of quality, and had to remind myself that just because something cost a lot doesn't always make it better, anymore than something being less expensive when new makes it worse. People who bought things new that have problems need to keep the lie going so they can sell them off to the next guy. It's rare the owner who exposes the Emperor being naked.


It's just perception based on successful marketing. Like "clean air initiative". Time always exposes the lies of man.

Does not the presumed success of Dry Boat assume a diligent owner has fixed the original reason for wet soggy stringers and core?

I have seen a number of way to attack moisture. In a sailboat keel I saw an air-conditioner vacuum pump intake tube glassed in and it ran for days sucking out the moisture I have seen shop vacs used and burned up from 24 7 sucking. I thought about it and if you can make the infected area air tight then first shop vac it with a small hole opened to allow air to cross the infected area. Then rent a wet tank of nitrogen, glass in the feed tube and let er blow, but do not over do, just a steady flow less than 2 psi. you don't want to ballon and delaminate. I have dried out telco cables under streets this way, worked good. I do not know anyone that has tried that on a boat. After drying I guess pumping resin into the voids would work. Caution, nitrogen in a closed unventilated space WILL KILL YOU. Though it is inert it is heavier than air, will displace the air in your lungs and you cannot dispel it. Odorless, no warning, just dead. So ventilate.

sunchaser said:

Does not the presumed success of Dry Boat assume a diligent owner has fixed the original reason for wet soggy stringers and core?

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Not really, they are two separate issues.

Don’t get me wrong, finding the cause was an important goal for me( once is definitely enough), but when I got estimates from repair facilities to tear out and replace, there was no 100% guarantee (in writing) that my stringers would never get wet again, only a guarantee relating to their workmanship. However, I do feel I got a little extra insurance as a side benefit of the drying process. Dryboat used a number of different moisture meters, core samples, etc, but they also used an Infrared camera. One of the things they were able to do, which I thought was unique to this service, was confirm the suspected reason for the intrusion (limber holes) as well as identifying areas of secondary or potential intrusion. In my case they showed me a couple of hairline cracks on the stringers and an area on my transom where my depth finder was attached that might be problematic long term. These showed up with the IR camera, i.e. The path which the warmer, dryer air traveled through while drying was a possible path air or water (or anything else) could get in.

I'm kickstarting this old thread instead of starting a new one - any new news on Dryboat? I'm looking at a non trawler (sorry) as my FIRST boat purchase to see if i get into this enough to do a large spend - and the little gal i like has moisture but no rot in the stringers. Pricewise, i may be able to get a substantial deal due to this - and its still cheap eough to almost consider a use/have fun and dispose in a few years (there is NO current rot)

So, any new ideas on Dryboat and AM I CRAZY?

Wonderfully uninformative website: DRYBOAT® Structural Moisture Removal Services

Not much point in drying out rotten wood. Not much point in drying out wet wood if you don't stop it from getting wet again. Who worries about wet foam core (unless you leave the boat in freezing conditions)?

How does a potential boat buyer find out if a boat has a cored hull below the waterline?

The hull came out fine. Surveyor said: Soundings on bottom with a phenolic hammer were unremarkable, moisture meter readings ranged 150-180.

Everything I have heard is continued success. And I think their new website shows and says everything I need to know about the choices.... Really like the TV segments and Ship Shape TV highlighting the company

Not Crazy

I have seen the process and results. It is the correct procedure for older hulls and frankly newer too that have just moisture intrusion. For stringers and other interior structure you might run dehumidifiers in your cabin and affected areas and monitor to see if levels drop using that method. As long as you have eliminated the source you may win the battle that way albeit in a longer time frame but a win is a win...

Gmarr said:

I'm kickstarting this old thread instead of starting a new one - any new news on Dryboat? I'm looking at a non trawler (sorry) as my FIRST boat purchase to see if i get into this enough to do a large spend - and the little gal i like has moisture but no rot in the stringers. Pricewise, i may be able to get a substantial deal due to this - and its still cheap eough to almost consider a use/have fun and dispose in a few years (there is NO current rot)

So, any new ideas on Dryboat and AM I CRAZY?

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She was shrink wrapped for a year and a half and I'm wondering if she was wrapped with water in the bilge that kept her moist all that time. Dunno....

If it's the engine mounts you are talking about then with a year and a half of rot in them I would suspect the engine beds would likely collapse. If you're talking about the odd stringer or longitudinal reinforcement as long as you don't abuse the hull and try to do a Bahamas crossing you should be fine (for a couple years). But...... If it's in the engine beds you risk totaling the transmission, shaft, struts wheels.

Was this all over? Or in one particular area? If it's in one area I would suggest finding out the source of the leak. It may be repairable. Then once you stop further ingress of water you could work on the wet stringer issue. Things I would be suspect of: Shoddy seacock installation, crappy hurricane damage repair, and underwater lights installed shoddy.

ancora said:

How does a potential boat buyer find out if a boat has a cored hull below the waterline?

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State the name of the boat and year made. You would be surprised how many lurkers here may have had one. Also, Do a search for that manufacturers forums to ask other owners.

Mainly in the engine compartment of the boat. It also was spotty, meaning not consistent and there is no current delamination or rot going on. The surveyor believes that intervention (and finding the culprit areas) will lessen the issue and perhaps halt proceeding to worse circumstances).

Don't understand why people keep bringing up the R word? GMARR stated at the start of his inquiry that the surveyor reported no signs of rot or delam. Sounds like exactly the issue I had with my stringers and the process worked great as it did for other people I talked to. Call Sea Ray and Meridian service like I did as well as talk to surveyors who are familiar with the process. The one I talked to supported it totally

Cruisers, what kind of boat did you do it on? I'm assuming you are talking about dry boat..... Did you also try any other forms of remediation that you could give feedback on that didn't work?

ancora said:

How does a potential boat buyer find out if a boat has a cored hull below the waterline?

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it's quite easy to see the core at transition points inside the hull. i.e. chines, strakes, transoms etc. Also an experienced surveyor can tell just by tapping the exterior with his little brass hammer.

Sorry....yes I used Dryboat on my Cruisers stringers....if you read back to beginning I started this thread exactly where you are wondering about their system