Fixing foam block

mdelaney

New Member
I am wondering if anyone has ever tried to fix a loose foam block from the bottom of the boat? I have read how to fix them, but was thinking about drilling holes in the hull itself, using the foam can spray to adhear the foam to the hull and then reglassing the hull. I realize that you never want to drill a hole in your hull, but this seems easier to me than trying to pour the foam through a port hole.

Also, has anyone tried the foam spray from a can and what were the results?
 
It's a lot easier to create an inspection port that repair a series of holes in the hull. The number of holes needed would be many and the time needed to do a proper repair on the holes is prohibitive. The block needs to be refastened it's entire length top and bottom to provide support to the deck and hull. Drilling holes in the deck would be ugly with no way to hide it except a total repaint of the deck.

I've use Foam-In-A-Can but would not recommend it for reattaching blocks. You need Two-Part-Foam that will flow in between the hull and block. Not much flow to Foam-In-A-Can. In fact, Canned Foam like 'Good Stuff' expands so much you can break the hull if the foam is not able to find a way to squeeze out of an opening.

http://www.windline.net/project3.htm
 
. . . has anyone tried the foam spray from a can and what were the results?
There are prior posts saying spray foam has worked for some and not for others. I believe some of the differing experiences have to do with how actively the boat is sailed, whether or not the foam was shot into a clean dry space, and what grade of foam was used.

In reading through the DOW Great Stuff MSDS, tech specs, and even trying some myself, I have discovered the following…

Spray foam comes in several varieties and brands. The density ranges from a light weight, high expansion insulator to a contractor grade low expansion sealer. The highest grade (and lowest expansion) has a density around 1.8 lb per cu ft.

DOW Great Stuff
http://greatstuff.dow.com

Density has to do with the ratio of the plastic forming the bubbles to the air trapped within those cells. The lower the density the larger the bubbles and the thinner their cell walls. Thin cell walls are subject to crushing (Compressive Deformation is the test category) at lower loads and are more easily permeated by water vapor over time.

Marine grade A/B polyurethane pour foam has a minimum density of 2 lb per cu ft to meet USCG requirements. We aren’t governed by the rule since we aren’t builders and our boats are sailboats under 20’ long, however that measure does provide a benchmark. The original foam used in a Sunfish is no doubt at least 2 lb density and several Sunfish owner’s, myself included, prefer using a 4 lb density foam in repairs.

Examples of different grades of A/B foam.
http://www.uscomposites.com/foam.html
(scroll down the page)

Closed Cell Foam
501388600300jpg_00000048043.jpg
 
"...The block needs to be refastened it's entire length top and bottom to provide support to the deck and hull..."
How about this alternative?

My Sunfish has both forward blocks loose, and a 6" port, but I'm thinking of a mechanical repair, such as making a couple of springy fiberglass struts. They'd be designed to keep both blocks pushed outboard in support of the deck. (And maybe gradually move back in their former place with wave action). Otherwise, I'm not inclined to do a proper foam repair for my "recreational-use" Sunfish.

My Porpoise II had good foam "glue", but the aft foam blocks themselves were like soaked sponges! Two of us could barely lift it after I'd purchased it. Handful by handful, I've since removed all the foam blocks aft of the cockpit.

Because the Porpoise is quite narrow (compared to the Sunfish), the aft blocks aren't missed. Flotation was restored with as many empty and sealed 2-liter plastic bottles as I could cram into the space. :eek:
 
Thanks for the responses. The last question I have is, has anyone tried to spray the two part foam in between the blocks and the hull? I am not sure how this could be done, but would think that a wand of some sort with an airless sprayer would be ideal and less mess. Any thoughts?
 
without doing a lot of research in archives has the possibility of separating the top and bottom hull sections ever been tried? i've seen this done on a number of other boats, on a small hull like this it seems like it's doable. not having a fiberglass SF i don't know if it is. just a thought.
 
has anyone tried to spray the two part foam in between the blocks and the hull?
It can be done, but unless you own the equipment, the pre-packaged commercial spray kit for 2 lb density marine grade comes in sizes uneconomical for a small job.

http://www.marinefoam.com/handi-foam.html?page_type=flotation-foams
handi-spray-in-foam.jpg




Have you looked through the pour foam procedure guide at the Wind Line Sails web site? http://www.windline.net/project3.htm

Wind Line Sails, Sunfish and small boat repair pages - Fixing a Loose Block
new-8.jpg



There is also a companion photo essay to the Wind Line Sails guide showing how to get good access inside the hull and details about handling the materials. It can be viewed and/or downloaded from Sunfish_Sailor.
http://groups.yahoo.com/group/sunfish_sailor




without doing a lot of research in archives, has the possibility of separating the top and bottom hull sections ever been tried?
It's do-able, but due to the complexity it's considered a last resort best reserved for someone with either prior small boat hull repair experience or the patience to climb a very steep learning curve. Not recommended for anything less than full flotation block replacement or very extensive hull/deck repair.

Subtleties like maintaining hull "squareness" and deck crown creep into the picture, not to mention repairing anything marginal discovered along the way. That approach can turn a $40 weekend job into a $400 month long restoration.

An outline of the procedure is in the Knowledge Base...
  • Sunfish KB & FAQ > Repairs & Upgrades > Replacing Foam Blocks [PDF]
    (Courtesy of the Sunfish_Sailor Owner's Support Group)

LP Factory Tour, Photo - Geophizz
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addendum (12-08-09):

Shortly after my last post I emailed DOW and inquired about some of the new foam-in-a-can products they've introduced recently. Products like backyard pond repair foam and their "Pro" contractor grade foams, stuff that comes in an economical size, but we don't usually find in the retail stores.

I explained the application was for bedding styrofoam emergency flotation blocks in a boat. That the bedding wasn't to be considered part of the flotation - just attachment. However it is desirable the foam have substance in the range of 2 lb density or better. And, if not the home foams then what is their recommendation for a product suitable for use in a marine environment.

No reply now after a week :(

If they are just busy and slow to get back to me, I will post the response when it finally shows up.
blink.gif



... it is convenient. Hope they now have something that will work for us.
 
addendum (12-08-09):

Shortly after my last post I emailed DOW and inquired about some of the new foam-in-a-can products they've introduced recently.

DOW replied today {Jan 12, 2010}, but not in the way I'd anticipated. They sent a survey asking how their customer service was/is. Considering nobody from DOW ever bothered to address my question, you can imagine the rating I gave them. :mad:

I left the door open for them to follow-up, we'll see... :rolleyes:
 
Dow Chemical huh?, ask them about directions for use of 'Agent Orange' and see if you get another 'Customer Care' survey.
 
Dow Chemical huh?, ask them about directions for use of 'Agent Orange' and see if you get another 'Customer Care' survey.
Wasn't that Monsanto? Anyway, the instructions are right on the side of the RoundUp bottle under active ingredient 2-4-D. But this is getting off-topic, I just want to fix Sunfish, not defoliate them. ;)
 
Actually it was both companys. Anyway when you submit a email question to a company most of the time it goes into a Rule-Based Auto Answer computer program. The program looks at syntax and key words and then tries to select a 'canned' answer that best fits the question. This may have been the response you got.

Or....

The Rule-Based program can't make a match and sends you're question to a computer work-station. Here the temporary employee, who's job is to make customer questions go away so he can surf the internet, mashes together some pre-canned answers that have nothing to do with the question and sends you a useless reply. How do I know this? Don't ask!

How to bring the topic back to Sunfish? I guess the short answer is that one comes to the conslusion that sending customer questions to most big companys is useless and uses the time to go sailing. Cold weather has had me dreaming of SF Sailing anyway!:D
 
I fixed one of my boats using foam in a can "Great stuff". What I did was found flexible tubing that could fit over the spray nozzle. On the other end of this tubing I attached a stiff tube that could be used to spray foam in otherwise impossible to reach areas. Keeping the can outside the porthole I was able to use the tubing to inject foam exactly where it was needed.
Though I probably should have used a denser foam this method was easy and economical.
I am happy with the results. Its been three years and the foam is still firmly attached. Also my boat weighs the same as it did the day I did it. It appears that the foam is not taking on water, although my boat leaks very little and I take time to thoroughly dry it out after each use.
 
I fixed one of my boats using foam in a can "Great stuff". ...I am happy with the results, ...although my boat leaks very little and I take time to thoroughly dry it out after each use.

I agree, that sort of easy application is exactly what's needed. The reason it's been shied away from is, if you dig out the technical info on Great Stuff, the most rugged level, the "Pro" variety in the low expansion grade, it still falls below 2 lb /sq ft density. If one doesn’t care for their boat as well as you do, the light weight foam is more susceptible to compressing from outside pressures and the thinner cell walls are less resistant to letting moisture vapor through over time.

DOW recently showed the addition of some new types of foam and a whole new level of contractor grade products, now available in cans rather than bulk only. My question to them was/is what’s the density of these new products (they seem to like to keep that a secret) and would any of these products be particularly suitable in a marine environment.

In my inquiry I never mentioned Sunfish specifically, just boat building and maintenance so DOW could relate the question to general foam block attachment that’s common practice in most all boat’s under 20’ and has, for decades, been the area where 2-part pour foam in the 2 to 4 lb density range is used. I would have thought if they had a suitable product, they’d jump at a chance to explore a new market.
 
Just wondering, did the foam flow around the edge of the block so that it sort of locked the block in place by forming a ridge between the deck and foam block?
 
Just wondering, did the foam flow around the edge of the block so that it sort of locked the block in place by forming a ridge between the deck and foam block?

On mine the blocks detached from both tops and bottoms near the dagger trunk. The fronts were tight and attached, so I left them alone. Next, I removed, (with a long hack saw blade), all of the factory expanding foam, from mid way all the way to the back. This left a 5/8” gap on top as well as bottom .I then used a long extension tube attached to the medium expanding foam (not the “Great Stuff” product) and started filling the entire void. It seems to have worked fine for now, the blocks are stable and the new expanding foam seems to cradle them nicely. I keep the boat aired out after use and all looks good.
 

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Received today from Dow...

Sir,

Thank you for contacting The Dow Chemical Company.

You had written in looking to find a spray foam that could be used in a boating application. Unfortunately none of our products have been tested for any aquatic applications. So we won't have a recommendation for your application.

If you have any questions, please call us at 866-583-2583 Monday through Friday from 8:00 am to 5:00 pm Eastern Time

You can also visit our www.styrofoam.com or www.dowbuildingmaterials.com web site and use the ANSWER CENTER link for technical questions 24 hours per day.

Best regards,

Jeffrey Sygo
Customer Information Group
Dow Building Solutions
The Dow Chemical Company
(866) 583-2583
www.dow.com

Less help than I'd hoped for.

I guess that makes us the guinea pigs for the next decade should anyone choose to try the foam-in-a-can approach.

For myself, I'll stick with marine 2-part foams because their properties are clearly stated and their performance is known.

.
 
While I think the 2 part is probably the best, I am still looking for an easier method. I recently found a product called Marine Evercoat Sealant Foam, by Evercoat, which they advertise as waterproof. I called the company to inquire about the density and the Tech I spoke with did not know. They are supposed to be checking with their development people and are to call me back. I will advise once I hear, if I hear. But in the mean time, has anyone tried this product? The negative on the Great Stuff seems to be related to it not being waterproof, this in the other hand is by a marine company and is water proof. I am intersted but still waiting.
 
The negative on the Great Stuff seems to be related to it not being waterproof
In the real world there's waterproof and then there's waterproof.

Plastic foam comes in two main structures, open cell (not waterproof)... a sponge for instance, and closed cell (what's called waterproof)... pool pasta, food coolers, and of course, our boat's emergency flotation.

Of the closed cell variety there are different plastics ... polystyrene and polyurethane are the two formulations we are concerned with. Polystyrene is the stuff the emergency flotation blocks are made from. Polyurethane is the stuff the blocks are bed into to adhere them to the hull.

Both these types of plastic foam are "waterproof"..., but there are differing degrees of waterproofness.

Both plastics form an extremely good barrier against water in it's usual liquid form, however, when water changes state from a liquid to a vapor the whole equation get more complex.

As a barrier against water vapor we need to look closer at the plastic's molecular structure. Under the microscope, all materials are porous and our foam's plastic walls are no exception.

Like a party balloon resists the passage of air, our foam's cell walls resist the passage of water vapor. How well they resist so they won't become waterlogged over time relies on one main factor, wall thickness.

Cell wall thickness in a foam is determined by air pocket size in relation to the amount of plastic surrounding the bubble of air. We refer to this ratio of plastic to air as a foam's "density". The denser the foam the more resistance to water vapor penetration it has.

The other quality foam possesses with relation to density is its ability to hold weight without collapsing. Again the denser, the stronger.

The issue with Foam-In-An-Aerosol-Can is, being that it's developed primarily for insulating in a dry-ish environment. The quality most valued there is maximum air bubble size. So, even in its "low expansion" version the plastic to air ratio has been found to be less than or just equal to the minimum level desired for marine use. (2 lb/cu ft - as outlined in the USCG boat builder's guide book).

Since the way our boat also applies the emergency foam as hull stiffening, we are doubly interested in foam density. So far, Great Stuff - Contractor Grade and its counterparts in the marketplace have only been shown to meet minimums.

The quest is to find a suitable spray foam that will be both easy to apply and rise above the minimum density to meet our needs. I'm hoping to hear you've discovered the grail.
 
I have a couple of quick questions regarding the foam blocks. Are they there just to support the weight of the top of the boat? I would think that there is never much weight on the deck of a sunfish anterior to the mast tube, but there are three foam blocks. I ask this because I am refurbing a 40 year old sunfish that I am starting to think all the block are loose. I am deciding if I should leave them alone, tear them out, or try to glue them back in with foam. My other option is to make a fiberglass tube, cut it to lenght, and wedge it in as a brace bewteen the deck and hull and then slap some epoxy with filler around the base and top of the tube to glue it in.

I should also note that the edges of the foam blocks are rounding off, like they have been loose for some time.
 
The foam blocks keep both the deck and the hull rigid, all are needed. Using a single tube as you mentioned would not work. All the stress would be on one small area and the unsupported areas of the hull and deck would flex. Try securing them with expanding foam. Making fiberglass tubes for a 'block to block' wedge might be an option.
 
has anyone used the waterfall foam or aquascape foam like dow great stuff pond and stone? It seems like if it is designed to be submurged, then it should not absorp so much water. also, it is minimally expanding, so it seems like its density would be pretty high.
 
has anyone used the waterfall foam or aquascape foam like dow great stuff pond and stone? It seems like if it is designed to be submurged, then it should not absorp so much water. also, it is minimally expanding, so it seems like its density would be pretty high.
Those new varieties of DOW foam were included in my original inquiry. Judging from the vagueness of the reply, I'm wondering if these foams do hold when surrounded by a high moisture atmosphere, but in their intended use it would make no difference whether they become waterlogged or not. Remaining unsaturated and light weight probably isn't part of a garden pond's functional criteria.

home_garden_pond.jpg
 
Such a soothing picture.

Now, do I go right of the lilly pads, and get inundated by the waterfalls, or do I go left where the green stuff is threatening to slow me down, but where there is more pressure?

PS: Racing radio-controlled fishes, of course. The starting line is on the right hand side, just outside of the picture. And the frogs agreed to volunteer for RC.
 
Has anyone considered installing the cubitainers from a laser in the hull of the sunfish, instead of trying to pour in expanding foam for the foam blocks. Especially is you added some hull-to-deck support?
 
Has anyone considered installing the cubitainers from a laser in the hull of the sunfish, instead of trying to pour in expanding foam for the foam blocks. Especially is you added some hull-to-deck support?
That would be great, but what do you do for reinforcing the hull? The styrofoam blocks act as stiffeners.
 
Would not be legal to race. I think it could be done if...

1. Foam blocks behind the tub remained in place.
2. The bladder would expand to provide support between the deck and hull without blowing the deck off.
3. You could make a bladder that is the right size. I don't have a clue how this could be done.

The whole thing would be much more complex then simply gluing the blocks in place. It would also be less robust than foam blocks. For those who like a to experment, it would be interesting. Might be able to knock the hull weight down to 100 lbs. Failure would most likely mean looking for a new hull.
 
OK, Looking for some guidance. I have removed all of the old foam that was holding my blocks in place and now getting ready to re-attach them. I think I want to go with the two part pourable expansion foam. Does anyone know approx, how much is needed. I have seen it on a few web sites, but not sure how mch to buy.

Also, in an effort to make the hull stiffer I am thnking about putting a strip of balsa core down on the inside of the hull. Any thoughts on this from you experts.
 
When you get the foam blocks doing what they should do, the hull will be stiff. Sometimes there is a problem with lack of support between bottom of the tub and hull. I used expanding foam but strips of foam wedged in would work. Anyway, just push on the bottom of the hull to check for Oil-Canning.
 

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