Machsquad

Soda blasting a hull

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I have a 25ft C&C that I am going to soda blast the old anti fouling off of. The big question is how many 50lb bags I will need to do the job? I will be using a industrial blaster and compressor. Any one have experience doing this? I have to order the bags in to where I am and don't want to be short or stuck with a bunch of bags left over.

Sanding is out of the question as I can't work in the positions required for the time required. 

 

Thanks.

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Depends on the blast pot valve style and nozzle size. What size compressor? Assuming at least a 185cfm compessor and a #4 nozzle, try 4 or 5 bags.

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Whereabouts are you going to be doing this blasting? I'd considered that as a possible route to a clean hull.

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3 hours ago, parclan said:

Depends on the blast pot valve style and nozzle size. What size compressor? Assuming at least a 185cfm compessor and a #4 nozzle, try 4 or 5 bags.

Its a trailer compressor but I do not know the exact specs for it.  Then the blaster and pot weigh 300lbs so they are fairly large. Only 4 or 5 bags that would be great. I had the idea of at least 6 and as high as 12 but I have zero experience with it so that was a blind guess. 

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3 hours ago, PaulinVictoria said:

Whereabouts are you going to be doing this blasting? I'd considered that as a possible route to a clean hull.

I will be doing it in Nelson BC at my house. I've built a rather large temporary shed around her as she needs some love this winter. This was the first time in 14 yrs she has been out of the water. Surprisingly good shape for being in the water for so long but I want to address all the minor issues before they become big issues. 

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Find something to practice on. A skilled blaster will remove all the antifouling leaving a slightly abraded gel coat.

But if you don't know what you are doing it is frighteningly easy to remove the gel coat and some of the layup as well. 

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2 hours ago, TQA said:

Find something to practice on. A skilled blaster will remove all the antifouling leaving a slightly abraded gel coat.

But if you don't know what you are doing it is frighteningly easy to remove the gel coat and some of the layup as well. 

I plan to use the rudder as practice as it is being completely rebuilt and needs a few fresh layers of glass. 

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Mach, you are a brave man. I had my boat blasted about 2 years ago (27 feet), and watched. I wouldn't never do it myself. But then I'm an older fart.

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I was quoted $3000 to soda blast my boat here in Nanaimo.  I am very curious how this goes as a DIY - please keep us posted.

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On 1/5/2019 at 2:38 AM, Machsquad said:

Its a trailer compressor but I do not know the exact specs for it.  Then the blaster and pot weigh 300lbs so they are fairly large. Only 4 or 5 bags that would be great. I had the idea of at least 6 and as high as 12 but I have zero experience with it so that was a blind guess. 

full face respirator mask with air supply... full body suit..

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On 1/10/2019 at 3:51 PM, Bull City said:

Mach, you are a brave man. I had my boat blasted about 2 years ago (27 feet), and watched. I wouldn't never do it myself. But then I'm an older fart.

Thank you but this is the lesser of two evils. Soda blasting will suck but sanding would be crippling for me to do. I'd only be able to do two hours of sanding before needing a few days at least to recover. So blasting it is. 

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19 hours ago, dash34 said:

I was quoted $3000 to soda blast my boat here in Nanaimo.  I am very curious how this goes as a DIY - please keep us posted.

Will do. I think it will end up costing me around $1000-1200. Everything gets here next week so I will update with costs and results. Also lessons learned, I'm sure there will be a few 

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20 hours ago, PaulinVictoria said:

I believe that soda is a lot more forgiving and gentle on the surface than glass/walnut etc.

Yes it is according to everything I have read or watched it should be more forgiving. So after next week I will be able to tell first hand if this is true. Also curious how it will do at removing fairing compound at the keel hull joint.

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3 hours ago, Grande Mastere Dreade said:

full face respirator mask with air supply... full body suit..

Safety is key. Planned for those

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Trick I was told was to keep the tip of the gun as far away as possible while still getting the coating off - don't "lean into it".

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You are a brave soul.  Find a beater boat and practice on that first.  I have seen the dark side of newbie soda blasting.

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13 hours ago, Machsquad said:

That makes sense. Avoid gauging the hull

you're going to want to fully tape and seal the top of the boat otherwise you'll be finding baking soda for years to come..

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Tough DIY project for a newbie and number of bags is highly dependent on equipment and extent of growth.

Will only add that if doing this I suggest doing a barrier coat before bottom paint.  Even an experienced pro is going to go through gel coat in places and in terms of overall project costs the barrier coat does not add much but gives great protection.  For both soda blasting and barrier coat, RTFM!!  :D  Go slow, be careful and good luck.

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4 hours ago, WoobaGooba said:

You are a brave soul.  Find a beater boat and practice on that first.  I have seen the dark side of newbie soda blasting.

I do have a 27ft fly bridge bayliner I am in the process of chopping up for the dump that would be a great test subject

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3 hours ago, Grande Mastere Dreade said:

you're going to want to fully tape and seal the top of the boat otherwise you'll be finding baking soda for years to come..

I am going to tape and tarp in the area I will be working on. Then I also have a industrial box fan that I will set up on inside with a discharge hose, creating a negative pressure where I am working and blowing the dust far away from the shed. This hopefully will be sufficient to prevent any dust or soda from making its way into the cabin or onto the top side.

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2 hours ago, Wess said:

Tough DIY project for a newbie and number of bags is highly dependent on equipment and extent of growth.

Will only add that if doing this I suggest doing a barrier coat before bottom paint.  Even an experienced pro is going to go through gel coat in places and in terms of overall project costs the barrier coat does not add much but gives great protection.  For both soda blasting and barrier coat, RTFM!!  :D  Go slow, be careful and good luck.

I will be fairing the hull after as well as applying a new barrier coat. There are some areas that need glass work done as well so if I do damage the gel coat it wont be the end of the world or really creating any extra work. I will try to minimize this but it is bound to happen.

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3 hours ago, Grande Mastere Dreade said:

you're going to want to fully tape and seal the top of the boat otherwise you'll be finding baking soda for years to come..

Soda blasting is the easiest blasting I have ever done. very mild blast effect, does get on everything but the advantage is it dissolves in water so it very easy to get rid of it  Boats are big so it does take awhile to do the whole boat if you don't have a high volume blaster.   The best for a bottom blast is to drape the tarps from the water line down to the ground and work under the tarp. almost no soda gets on the upper part of the boat that way

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3 minutes ago, Overbored said:

Soda blasting is the easiest blasting I have ever done. very mild blast effect, does get on everything but the advantage is it dissolves in water so it very easy to get rid of it  Boats are big so it does take awhile to do the whole boat if you don't have a high volume blaster

I will be using a high volume blaster. I am really looking forward to starting I don't think it will be a scary job to do. It will take proper precautions and steps to ensure safety but there shouldn't be any fires....  It's only a 25 ft boat so I should be able to do it in a day.

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Since you are barrier coating anyway, I'd suggest getting rid of the gel coat if you can and it doesn't end up costing a lot more money in bags of soda.  It doesn't do anything to stop osmosis, and once it is removed any water in the laminate will have a much easier time evaporating out.  Powerwash the hull a few times after you get the gelcoat off, preferably with hot water.  Let it get good and dry before applying the barrier coat.  You won't regret doing this, but it is an awful lot of work.  

 

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Proper safety gear is really expensive.

If you dont have access to a helmet and a proper filter to breathe the air from the compressor you will be shocked at the price.Been there done that.

It also takes some practice to get the equipment to work effectively for most folks so plan on burning through more media than you think.

Its really shitty work.

 

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2 hours ago, dash34 said:

Since you are barrier coating anyway, I'd suggest getting rid of the gel coat if you can and it doesn't end up costing a lot more money in bags of soda.  It doesn't do anything to stop osmosis, and once it is removed any water in the laminate will have a much easier time evaporating out.  Powerwash the hull a few times after you get the gelcoat off, preferably with hot water.  Let it get good and dry before applying the barrier coat.  You won't regret doing this, but it is an awful lot of work.  

 

That is a very good point. Once blaster I plan to wait a month or so before I start fairing. Partly for warmer weather and the other Part so it can dry out completely. There is zero signs of any kind of osmosis but might as well make the most out of it.

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1 hour ago, Bute Burnout said:

Proper safety gear is really expensive.

If you dont have access to a helmet and a proper filter to breathe the air from the compressor you will be shocked at the price.Been there done that.

It also takes some practice to get the equipment to work effectively for most folks so plan on burning through more media than you think.

Its really shitty work.

 

Since I had to order the media in I ordered 3 extra bags. Figured it was better to have to much then to run out half way through. Yeah the safety equipment isn't cheap but its better to be safe and alive then not. 

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2 hours ago, Machsquad said:

That is a very good point. Once blaster I plan to wait a month or so before I start fairing. Partly for warmer weather and the other Part so it can dry out completely. There is zero signs of any kind of osmosis but might as well make the most out of it.

I don't know if the boat you bought was kept in fresh water or salt water,  but...

Keep in mind blisters occur much more readily in fresh water than in salt water and the higher the lake water temp, the greater the likelihood.  So if it was a salt water boat, it may be only a matter of time after being immersed in a lake.  So yeah,  the barrier coat idea is a good one.

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2 minutes ago, 12 metre said:

I don't know if the boat you bought was kept in fresh water or salt water,  but...

Keep in mind blisters occur much more readily in fresh water than in salt water and the higher the lake water temp, the greater the likelihood.  So if it was a salt water boat, it may be only a matter of time after being immersed in a lake.  So yeah,  the barrier coat idea is a good one.

The boat has been in fresh water for 15 years but before that it was salt water. The rudder had issues but that was mostly due to a bad repair done 15+ years ago. The lake it was in does not get very warm. Best to do it right the first time.

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16 hours ago, Machsquad said:

I do have a 27ft fly bridge bayliner I am in the process of chopping up for the dump that would be a great test subject

Im liking that plan a lot.

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FWIW............

I had our Jeanneau 36 soda blasted two season ago, to remove hideous thick layers of bottom paint. First less was, make sure all the through hulls are closed! The soda blaster should have shoved rags into the through hulls................

The soda can leave white gelcoat yellowed if it isn't washed off right away. If this happens, just wipe vinegar on the area and it will return it to white.

 

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Good point about the trough hulls and I will keep the vinegar trick in mind.

Update is the soda media shipment was delayed. i just got word yesterday that it was in so Friday will be the day 

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On 2/10/2019 at 7:49 PM, Machsquad said:

Good point about the trough hulls and I will keep the vinegar trick in mind.

Update is the soda media shipment was delayed. i just got word yesterday that it was in so Friday will be the day 

I look forward to hearing your experience. I have access to all the equipment and I trying to decide if I should do it myself.

 

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All equipment and materials in place. I will be starting at 8 am tomorrow. Hopefully all the tape I used holds in the cold weather so the topside stays clean. Also ended up using scarp foam from the new cushions to plug all the through hulls. I have taken pictures and will take some though out the process, to be posted in here.

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So all and all I'd say it went well. It took about 2 hours to get everything dialed in well which caused a waste of media. 

I spent 7 hours blasting and would say I am just over 3/4 complete. The rest I will use a sander for. I ended up using all 8 bags and think that it would've taken at least 4 more to completely finish. My back would've kept me from being able to finish in one day regardless so I have saved a ton of time and made significant progress.

I found that the flow of media was very finicky, I would guess the humidity was the biggest cause of this. If I didn't stop and kept going everything would flow smoothly but once i stopped it would take about 30 min to get it all dialed back in and running properly. The blasting of materiel off was very forgiving, any where I took to much off it was a fraction of a millimeter nothing dramatic.

I did not remove the gel coat this would've taken a much courser media, the soda would strip it but very slowly. There was a purple and green fairing compound used around the keel joint that was very resilient and slow to remove. The white fairing compound that I assume was from the factory was very easy to remove. I exceptionally happy with how well I was able to clean up the keel joint as this was my biggest area of concern.

Lessons learned:

no matter how well you tarp and tap off the powder will find a way, 
ensure the plastic tarps are anchored to the ground so they don't get sucked into you while working
two people would be best (my helper cancelled)

This was a relatively easy job to do, I would recommend it. I would say that if using a similar set up to what I used plan for one 50 lb bag for every 2 ft of boat length.

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Would love to see your pics but they're not loading or blocked or something.

I'm faced with the same job, same size boat.

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20 minutes ago, blurocketsmate said:

Would love to see your pics but they're not loading or blocked or something.

I'm faced with the same job, same size boat.

The pictures should work now

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I had my hull sandblasted this past fall, if you have a lot of build up considering sandblasting as opposed to soda blasting is a thought. bottom paint and barrier coat are pretty tough stuff. 

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2 minutes ago, frozenhawaiian said:

I had my hull sandblasted this past fall, if you have a lot of build up considering sandblasting as opposed to soda blasting is a thought. bottom paint and barrier coat are pretty tough stuff. 

 I would be extremely careful if using other media like sand though, it may remove too much too quickly. The barrier coat and anti fouling were removed easily and quickly by the soda. Fairing compound was very slow to remove but if you only have a small area like a keel to hull joint I'd recommend the soda just plan for extra time and media. It was very hard to cause any over damage to the fiber glass.

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1 minute ago, Machsquad said:

 I would be extremely careful if using other media like sand though, it may remove too much too quickly. The barrier coat and anti fouling were removed easily and quickly by the soda. Fairing compound was very slow to remove but if you only have a small area like a keel to hull joint I'd recommend the soda just plan for extra time and media. It was very hard to cause any over damage to the fiber glass.

I do the vast majority of my own work but I had a pro come in and do the sand blasting. came out great. but you're right. 

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2 minutes ago, frozenhawaiian said:

I do the vast majority of my own work but I had a pro come in and do the sand blasting. came out great. but you're right. 

I would've happily paid someone else to do it but there is no one locally to do it. So I drew the short straw by default. It really is a very nice finish that is achieved by media blasting. 

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Thanks for the update.  Good to know that this works and is within the capability of a DIY.  I may get a new boat this year and it will likely have a big buildup of antifoul that needs removing.  The only problem might be finding a yard that will let me do it. 

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54 minutes ago, Machsquad said:

 I would be extremely careful if using other media like sand though, it may remove too much too quickly. The barrier coat and anti fouling were removed easily and quickly by the soda. Fairing compound was very slow to remove but if you only have a small area like a keel to hull joint I'd recommend the soda just plan for extra time and media. It was very hard to cause any over damage to the fiber glass.

I wouldn't let sand near a boat of mine. I've seen some bottoms end up looking like the Moon, even when done by pro's. Had to have glass laid on to smooth them out, not just barrier coat.

I've heard dry ice blasting is good and it leaves only dry residue because the medium evaporates - sounds great but I've never seen it or even pics, only anecdotes.

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I will say a blasting pot that has a vibrator on it would help greatly. The soda does stop flowing from time to time and tapping the pot would get it going again.

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Thanks!

The yard here only does soda blasting now to strip bottoms, using an outside contractor.  It's quicker and more consistent for them. 

They allow DIY but at $75/day rent.  With my own limited labor and tools, this could get expensive enough to just let them do the whole thing.

I never got the blasting quote, only the barrier and antifoul, so need to follow that up.  Sail magazine says $40/ft. -- not sure if it would be cheaper here.

 

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3 minutes ago, blurocketsmate said:

Thanks!

The yard here now only does soda blasting to strip bottoms, using an outside contractor.  It's quicker and more reliable/consistent/effective for them. 

They allow DIY but at $75/day rent.  With my own limited labor and tools, this could get expensive enough to just let them do the whole thing.

I never got the blasting quote, only the barrier and antifoul, so need to follow that up.  Sail magazine says $40/ft. -- not sure if it would be cheaper here.

 

It cost me $240 to rent the compressor and blasting pot for a day. Then $60 per a 50 lb bag of media. That should help you figure out if the quote is reasonable, but there is value in letting the pro do it that has all the right gear so depending on how dramatic the cost difference it may or may not be worth it.

 

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Question from a newbie on the topic...

I understand that soda is not harmful for the environment and the soda dust generated during the operation is easy to dispose of.

However, you are also removing anti-fouling material... and it comes out as fine dust as well, mixed up with the soda dust.

Isn't it an issue? I believe you were talking about blowing the dust out by creating a vacuum around the area being blasted...

I removed anti-fouling with a friend, on a much smaller boat, a few weeks ago, with scrapers; with the boat sitting outside. We put a tarpaulin underneath and collected as much as we could, afraid that the anti-fouling dust would end up in the pond right next to the boat, and kill all the fishes in the pond... Were we overly cautious???

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No I don't think you were overly cautious. When it comes to anti fouling if you didn't put it on, you don't know what kind it is and what chemicals are in it. So it is better to be safe than sorry. 

I put tarps down and caught as much of it as I could. The fan blowing air away was more then anything there to improve visibility. It was blowing onto the snow and did leave a red patch. It wasn't a very big patch so I am fairly confident that most fell to the ground or into the boat... The powder is a nice light red colour that I did catch. The powder is hard on the shop vacuum, plugs the filter in a few minutes of use.

I did make sure to wear appropriate breathing equipment and other safety gear. Pretty sure what I wore was over kill but better safe.

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I hope you enjoyed the experience and that you never come down with a respiratory ailment, like mesothelioma.

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Doesn't that require a lot of asbestos?

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6 hours ago, Bull City said:

I hope you enjoyed the experience and that you never come down with a respiratory ailment, like mesothelioma.

Thanks, same here. The hazmat gear I worn was meant for asbestos removal, so I feel pretty good about the level of safety. 

I would do it again, it really wasn't that hard to do or unpleasant.

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On 1/18/2019 at 3:39 PM, Machsquad said:

I will be fairing the hull after as well as applying a new barrier coat.

Good to hear this. Will you be checking for moisture with a meter?

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2 hours ago, Bull City said:

Good to hear this. Will you be checking for moisture with a meter?

I should but haven't yet. Need to get a meter would be the first step

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2 hours ago, Machsquad said:

I should but haven't yet. Need to get a meter would be the first step

Did you see any evidence of blisters?

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3 minutes ago, Bull City said:

Did you see any evidence of blisters?

The rudder was covered in two inch blisters. I cut it open and the foam core was soaked. So I removed the core and am currently rebuilding the rudder. The water got into the core through the bottom of the rudder, there was a 1/4 inch jet of foam through the fiber glass that soaked up all the water. The hull had one blister above the water line, still trying to figure out how water got there but I suspect it came down from the toe rail. Other than that no blisters under the water line on the hull. Might be a good idea to get some readings though, as they may help me find the ingress route at least. 

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Will the soda remove barnacle circles or would I have to chisel them all off first?

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3 hours ago, blurocketsmate said:

Will the soda remove barnacle circles or would I have to chisel them all off first?

Yes.

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1 hour ago, Ishmael said:

Yes.

Glad some one knew, I have never had to deal with a barnacle. Fresh water only so far

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14 minutes ago, Machsquad said:

Glad some one knew, I have never had to deal with a barnacle. Fresh water only so far

Muriatic acid, or lemon juice if you have principles and a lot of time. 

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13 hours ago, Ishmael said:

Muriatic acid, or lemon juice if you have principles and a lot of time. 

Good to know thank you

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23 hours ago, Machsquad said:

The rudder was covered in two inch blisters. I cut it open and the foam core was soaked. So I removed the core and am currently rebuilding the rudder. The water got into the core through the bottom of the rudder, there was a 1/4 inch jet of foam through the fiber glass that soaked up all the water. The hull had one blister above the water line, still trying to figure out how water got there but I suspect it came down from the toe rail. Other than that no blisters under the water line on the hull. Might be a good idea to get some readings though, as they may help me find the ingress route at least. 

How long has the boat been out of the water?

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17 minutes ago, Bull City said:

How long has the boat been out of the water?

5 months now but it is winter here so -5c to -15c for 3 months of that time.

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20 hours ago, Machsquad said:

5 months now but it is winter here so -5c to -15c for 3 months of that time.

If you have any concerns about moisture & blisters, or just curiosity, Nigel Clegg is a good resource:

http://www.passionforpaint.co.uk/Osmosis.htm

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