Rotten deck core. How detrimental?

[gansett]

We looked at an otherwise beautiful and well-kept Pearson 31-2. Included in the listing was his purchase survey from 2013 with an addendum listing all the deficiencies and if and when they were corrected. Clearly, a soft core in the side decks was noted, but never addressed by the owner. I did not do a moisture reading but i could detect a weakness in about a 5 ft length of the port side deck. He was open about it and how he felt his price reflected the deficiency, but also that it wasnt detrimental to the overall structure of the boat.
It was more of a red flag for my wife than I, but we did decline to make an offer for a variety of reasons.
My understanding is fhat wet and or rotten core is common among boats of this era and construction and that if it is not widespread or structural, it could be left for correction at a later date. But how big of an issue is it when not hull or structure related and how common is it in balsa cored boats?

[tkeithlu]

The deck is structural. It helps hold the hull in shape. You need to be able to repair it. The core is like the unstressed middle of an "I" beam, with stressed top (tension) and bottom (compression) layers of fiberglass.

[roverhi]

For most sailing a rotten core is no big thing. Mainly a nuisance with the springy deck. There's a Catalina 27 a couple of slips down from me with the entire foredeck mushy. The owner actively races the boat in the weekly beer can races and daysails regularly.

Is that a reason not to fix it, NO!! As Tkeithlu says, the whole deck is a structural system that relies on it's parts working together. The rotten core is caused by water leaking into the core and rotting it out. If you don't stop the leak the rot will only spread. Easy to fix the leak if you can locate it. Fixing the mushy deck is a major PITA and expensive to have a yard do it. Not a fix that is beyond most people's skill level but requires cutting and grinding, fitting new core, glassing over and and finishing.

Unless the boat is REALLY cheap and you wanted to take on a project would look for a boat without core issues.

[BlackHeron]

It's not going to get better on its own. Moisture is going to continue to spread and delamination is going to get worse and worse over time. The question is just how much time. Hard to tell over the internet, but the clock is certainly ticking. Best to consult an expert to do an evaluation. Your basic marine surveyor will not help much here other than tell you that water is wet, green money is green money, and thank you very much for your fee.

Keeping deck fittings from leaking is going to become less and less possible as deck flexation is going to break the seal on even the most forgiving of sealants short of butyl tape and even that will tend to fail as flexing and freeze-thaw cycles cause deck expansion and contractions. You can remove and rebed every effected through-deck at the damaged area on perhaps a yearly basis and maybe keep up with it.

As others have said the fix can be labor-intensive and the materials are not exactly cheap either. Messy hard work, but doable if you don't mind getting your hands dirty and your marina or yard allows DIY work of that major scope. That is something to check into before starting or even planning on purchasing a boat with these issues.

[Hardhead]

I think many people will say to keep looking. There are lots of boats available - and having a BIG re-coring job right off the bat is the stuff of empty wallets and divorces - especially with a only half-way interested partner. If you research "deck core repair," you'll usually see some fairly gruesome photos. Small job - not too bad, but the problem is you usually find it is much worse than first imagined. Rot travels... and you're invested.

[midnite44]

Originally Posted by gansett

We looked at an otherwise beautiful and well-kept Pearson 31-2. Included in the listing was his purchase survey from 2013 with an addendum listing all the deficiencies and if and when they were corrected. Clearly, a soft core in the side decks was noted, but never addressed by the owner. I did not do a moisture reading but i could detect a weakness in about a 5 ft length of the port side deck. He was open about it and how he felt his price reflected the deficiency, but also that it wasnt detrimental to the overall structure of the boat.
It was more of a red flag for my wife than I, but we did decline to make an offer for a variety of reasons.
My understanding is fhat wet and or rotten core is common among boats of this era and construction and that if it is not widespread or structural, it could be left for correction at a later date. But how big of an issue is it when not hull or structure related and how common is it in balsa cored boats?

There is a product called Instadeck , works great just did my entire fore deck , very easy to do , my deck was soft /spongey so I injected Instadeck as directed . It is hydroscopic and will displace / eliminate water between the deck . My deck is now as firm as it was the day it was laid up by Irwin boat builder .Go to InstaDeck.com for info on the product.

[zstine]

We purchased a boat with moisture in the deck and some small areas that were soft. While the deck is structural, many areas are not heavily loaded and I've never heard of a boat sinking because of moisture in the deck. It is mainly annoyance and can lead to cosmetic cracking of the gelcoat. We have had our boat for 8 years and sailed over 10,000 miles. The deck has not gotten noticeably worse (we did re-bed leaking hardware). If the price is commensurate to the issue, I would not walk away just b/c the deck issue. It is likely something that can be done a few years down the road at your convenience.

[bcboomer]

Originally Posted by midnite44

There is a product called Instadeck , works great just did my entire fore deck , very easy to do , my deck was soft /spongey so I injected Instadeck as directed . It is hydroscopic and will displace / eliminate water between the deck . My deck is now as firm as it was the day it was laid up by Irwin boat builder .Go to InstaDeck.com for info on the product.

All I find with that info is a Canadian company doing house decks.

[midnite44]

Try InstaDeck.com It's a good product that is hydroscopic and will displace/eliminate water , just did my whole foredeck and it is now as firm/stiff as it was new , it's an easy product to install just follow the instructions carefully , it's not expensive and works . I worked at a Megayacht shipyard an we would use this product for small (!0sq.ft. ) areas with good results . for your vessel you can use it for the entire deck you'll be happy with your results , just follow the instructions carefully .

[zstine]

Originally Posted by midnite44

Try InstaDeck.com It's a good product that is hydroscopic and will displace/eliminate water , just did my whole foredeck and it is now as firm/stiff as it was new , it's an easy product to install just follow the instructions carefully , it's not expensive and works . I worked at a Megayacht shipyard an we would use this product for small (!0sq.ft. ) areas with good results . for your vessel you can use it for the entire deck you'll be happy with your results , just follow the instructions carefully .

I'm guessing you mean https://injectadeck.com/ ???

[OS2Dude]

+1 to 'BIG DEAL'. As stated above, the core gives strength to the hull. Not to mention without a good core one day someone will fall right through the deck when the rot destroys enough of the core. And until the source of the leak is found and fixed, it will continue spreading and weakening the boat.

Like anything, rot can be ignored and all will still be OK until the day when it isn't and a small to large failure occurs.

[skipmac]

Have a 1984 Pearson 42 and found a few areas of wet and rotten core but most were just a few inches around stanchion bases and such.

My take on how big a concern, depends on how big the problem is. Damp decks or small areas of rot and delamination are not a killer unless you're sailing across oceans or high latitudes. And as noted, can take years to get worse BUT you would need to rebed and stop further water intrusion.

A 5' area could be serious but will depend on how bad it is. So how weak was it? Did the whole 5' section deflect in a half inch when you stepped on it? Was the whole area springy and flexing? How did this compare with the other side of the deck?

AND a big question, how good a deal and how much time (or money) are you willing to invest to get a good deal.

I will add that 99% of older boats will have some degree of leaking and water intrusion.

[Rick Williams]

It depends on if you want to be a boat builder or a sailor. My experience with soft decks is that they are a lot of work and wayyyyy more than you can imagine. Whomever said there's a lot of boats out there was correct. There are thousands of boats whose owners have used them and now need to let them go and kept them in perfect condition the whole time they sailed them. Spend your time looking for those boats, not learning how to replace soft decks. In hindsight you'll find it's a nightmare you don't want.

[Rorzech]

Originally Posted by gansett

We looked at an otherwise beautiful and well-kept Pearson 31-2. Included in the listing was his purchase survey from 2013 with an addendum listing all the deficiencies and if and when they were corrected. Clearly, a soft core in the side decks was noted, but never addressed by the owner. I did not do a moisture reading but i could detect a weakness in about a 5 ft length of the port side deck. He was open about it and how he felt his price reflected the deficiency, but also that it wasnt detrimental to the overall structure of the boat.
It was more of a red flag for my wife than I, but we did decline to make an offer for a variety of reasons.
My understanding is fhat wet and or rotten core is common among boats of this era and construction and that if it is not widespread or structural, it could be left for correction at a later date. But how big of an issue is it when not hull or structure related and how common is it in balsa cored boats?

Nobody ever had a boat sink because of a rotten core. After hearing that I bought a boat with spongy decks. I decided to drill a pattern of 3/16" holes in the deck 6 " apart in grid fashion. Then I got a can of 2 part foam from home depot. I proceeded to inject all the holes with a fair amount of foam and let it cure over night. The complete deck is as hard as rock and now i wonder if a spongy deck is more comfortable to walk on now. Too late to change my mind now . Looks like i'm stuck with a perfectly hard deck to walk on for a mere $67.00 can of foam.

[Boatyarddog]

Originally Posted by midnite44

There is a product called Instadeck , works great just did my entire fore deck , very easy to do , my deck was soft /spongey so I injected Instadeck as directed . It is hydroscopic and will displace / eliminate water between the deck . My deck is now as firm as it was the day it was laid up by Irwin boat builder .Go to InstaDeck.com for info on the product.

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