Divinycell alternative
 

Similar to Divinycell in strength and composition, #624/625 6# mix-and-pour foam for structural void fill applications seems interesting to me.

Divinycell is used as a wood substitute by some boat builders. While thinking about how to never ever have to deal with rotted stringers and transoms, I wonder if there may be an alternate means to correcting these issues. Rather than cutting up a boat to replace transom and stringers, has anyone tried or know of anyone that has tried this to correct rot by removing it and filing the void left in the fiberglass with a very strong material which can take on shapes something like wood or sheets of Divinycell cannot.

Logical steps;

1) remove existing rot - there must be a way to drill through glass and into rotten wood and extract it?

2) seal up all entrance paths into transom stringers except for a few where you will install a temporary valve.

3) shoot pressurized #624/625 6# mix-and-pour foam into the transom and stringers using the valves installed (what does Boston Whaler use?)

4) cure.

#6 is not quite as strong as divinycell but it is quite strong and it seems to have a much more flexible application which could facilitate design enhancements.

If this works, it could possibly save a lot of old go-fast boats fairly quickly, hopefully cost a reasonable rate (less labor), removes future thoughts of rot, increase retail value?, help them float better?, etc.

I know, probably a dumb question..or maybe a million $ idea?

its done all the time but you have to be vary careful of how, where and what is used. I dont care for foam in stringers and transoms because of how it handles compressive loads over time. Every race boat we had with composite transoms developed some kind of issue from "eye browing" at the top and bottom to actually crashing props together on a close stagger setup to breaking inner transom plates. Wood does not rot because it is wood, wood rots because of how it is installed (if poorly) and cared for. Composite transoms are great for the average boat but i think as high performance loads go up it struggles. I'm sure there are higher performing products used in Mystic and the like but probably not cost feasible by us mere mortals lol. As of yet i'm still not a fan of composite transom and stringers and i am sure some will argue
:cool:.

Forget about any kind of pourable anything, those are junk temporary fixes. Six pound foam is to light for transoms. Transoms require something in the twenty four to thirty pound range. I did a 28 foot CC cat for the USGS here in the great lakes that was a 100% composite rebuild. All Coosa Bluewater 26 throughout and the transom was three layers of half inch BW26 with a full lamination of 1708 between each layer. Bad ass boat that will pretty much last forever. Something else to note when using composite panels, you should always use an advanced resin system above polyester. Vinylester or epoxy at a minimum, poly does not have the elongation to work properly with foam.

coosa or Penske composites or Space age composites as many builders use that for transoms as well

Some have had there share of problems with using these materials thru out.

Cobalt went back and forth with what materials to use for years and have found one that is here close by me. I forgot the name but have to relook it u anyways. I will post it when I find that info.

this is an interesting thing i stumbled across recently....its a pourable ceramic transom repair compound...not sure what exactly it is..but still interesting...

http://arjaytech.com/index.php/our-p...able/6011-6012

I suspect there would be a number of challenges to work out. I contacted Arjay (who makes the product noted above) and they have a 6011 ceramic pourable compound (CPC) that they state is being used in boat transoms and stringers. Logically it seems as though it would be possible to open the top of a stringer or riser, remove the rot and pour the 6011 in from the top and then glass over these openings. It feels that would be a reasonable solution for "non racing" boats and would even be pretty easy for stringers.. I would think the transom on the other hand would be a bit more challenging purely because of size., however with the transom de-rigged and rot removed and something like plywood braces on both sides of the transom, you should be able to pour 6011 there (and when done cut out the holes needed on the transombased on the hole outline in the existing transom. For added strength I wonder if an application like rebar in concrete might be applicable here? In the end it may or maynot be more work, I guess it all depends on the difficulty of removing rot and the value in preserving the existing framework left behind by the fiberglass that has been hollowed out by wood removal.

I know many of you are the sort of perfectionists that when your front right brake starts to squeek on your car, you "do it right" and replace all pads, rotors, calipers and brake fluid...maybe even brake lines and the master cylinder. However, not all of us need that degree of perfection because we do not push as hard. To that extent, I wonder if this CPC could also be used to "patch" rot. For example if only the bottom couple inches of the transom showed rot and it was rock solid above, could you pour something like 6011 into that space? (curious, if this happens and a more traditional approach to transom repair is done, would wood be used to patch this or would the whole transom be cut off and replaced?

If so motivated to test this out on a small scale without potentially destroying a boat, what might be a valid test? I could certainly pour the stuff between a couple pieces of plywood or sheetrock, but how would I test the strength?....but then again the manufacture has probably already done this.

Just doing some creative thinking.

Has anyone tried this and/or know of anyone trying this? It appears as though there is a specific product developed for transom repair (and I would assume it would apply to stringers as well) - http://www.carbon-core.com/carbonbond-transom.htm

I would expect difficulty filling the voids with a pour product. How would you vent the voids adequately to allow flow ?

By voids do you mean air pockets that may form during the pour? or are the voids you are thinking of cutouts in the transom for things like exhaust? or something else? ...great quesiton.

Air Pockets - First thought that comes to mind when resolving air pockets might to be to use a method similar to pouring concrete - poke it with a long stick to free air pockets by allowing them to rise to the top. This same technique could be used to move product into areas where there is not enough gravity to push it there. I also suspect but don't know if this product expands at all. I suspect not but if it does, that could help with distributiuon. A slow pouring may also help here.

FIlling Transom holes/cutouts. - here I would fill these with wood or styrophome depending on how expansive the foam is. Alternatively, I might cover the holes (front and back) with plywood and pour these as a transom component, then after drying I would cut these pieces out..

I suspect there are probably better methods of doing both, so I would speak with the company and get their feedback on both.

I can't imagine there being much of a labor difference in a) cutting out and replacing the stringers with wood or composite, and b) cutting open top of stringers, removing rotten wood, pouring whatever substance, and reglassing the top of stringer.

Option b may even take more time to prep surfaces for bonding.