Mixing my own transom pour

[gjmsd]

I'm considering mixing my own pourable transom. I've research the available product out there and everything I find seems to be out of FL. HazMat shipping to San Diego on top of the product cost makes it a bit pricey so I've been thinking of buying local ingredients and mixing my own. Based upon the density of the finished product, I'm guessing the popular brands are about 40% poly and 60% ceramic microspheres. My first question is would epoxy be a better than polyester resin? Which would flex better without cracking? I'm actually going to try a test mix with 1/3 resin (one of each), 1/3 ceramic microspheres and 1/3 chopped glass and test it. Any input from those that have worked with this stuff would be appreciated.

 

[ondarvr]

Re: Mixing my own transom pour

Yes you can make your own, all the fillers to do it should be available locally, what you run into though is finding the right resin. What you need is a somewhat long gel time with a suppressed exotherm ( the heat at which it wants to cure at in a mass). Laminating resins are designed to cure in a 1/4" thick or less layup, so at 1.5" it will get too hot. You either need to find the right resin, or the right catalyst, there are blended catalysts that will slow the cure and reduce the temperature dramatically. Finding a retail outlet to sell you one of these may be a little difficult because they will need to special order them.


As to which would be better, epoxy or polyester, epoxy is almost always better, but cost can be an issue, VE would be about mid way between the two in cost.

 

[gjmsd]

Re: Mixing my own transom pour

To do the job, epoxy would be about $120 more. I'm fine with that if it would be better. I've already purchased the ceramic microspheres and chopped glass. The microspheres are supposed to reduce the exotherm signicantly. I'm more concerned with cracking if the transom flexes since I'm putting a larger engine on (135hp, the boat is rated for 125hp).

 

[i386]

Re: Mixing my own transom pour

I think it's risky ordering the materials to make a DIY pourable transom without a known working formula. I'm sure the companies that sell these products didn't get it right the first time. I wouldn't think I could either. If I had cheap access to a lot of different resins hardeners AND knew how to properly test it it might be a different story.

 

[ondarvr]

Re: Mixing my own transom pour

Fillers do cool it down, but its still fairly thick, so it will get warm (hot), how do I know...I used to make it long before you could buy anything like it. I also used a blended catalyst with it, had to blend that myself too.

Epoxy will get hot too, so when you get the hardener make sure you get the right one.


On cracking...Since the current ones on the market are polyester, and I haven't heard of them failing, all three resins will probably work OK.

 

[gjmsd]

Re: Mixing my own transom pour

I think it's risky ordering the materials to make a DIY pourable transom without a known working formula. I'm sure the companies that sell these products didn't get it right the first time. I wouldn't think I could either. If I had cheap access to a lot of different resins hardeners AND knew how to properly test it it might be a different story.

Believe me, I've thought long and hard about this. Being a mechanical engineer I appreciate the complexity of the mixture and its properties. The purpose of the core is to provide a rigid separation between the two layers but it needs to be able to flex somewhat without cracking. Things made too rigid can cause failures elsewhere. I also plan to make it in several smaller batches instead of one large one to allow the heat to dissipate after each pour. As long as the mixture has good adhesion, resists cracking and isn't too heavy, it should make a good core.

 

[gjmsd]

Re: Mixing my own transom pour

Fillers do cool it down, but its still fairly thick, so it will get warm (hot), how do I know...I used to make it long before you could buy anything like it. I also used a blended catalyst with it, had to blend that myself too.

Epoxy will get hot too, so when you get the hardener make sure you get the right one.


On cracking...Since the current ones on the market are polyester, and I haven't heard of them failing, all three resins will probably work OK.

I'm figuring if I use a warm weather formula in slightly cooler weather, it should slow down the hardening and reduce the exotherm.

BTW. Do you remember what all you put in your mix and how did it turn out. Feedback from people who have done this before is really helpful.

 

[jonesg]

Re: Mixing my own transom pour

For the price of quality epoxy, you might be better off buying Nidacore, its half the cost of seacast. They'll send you a gal pail just to sample.

 

[gjmsd]

Re: Mixing my own transom pour

For the price of quality epoxy, you might be better off buying Nidacore, its half the cost of seacast. They'll send you a gal pail just to sample.

I talked with them, they will only send a free gallon if you have a business (with a license) in the composite industry. Nidacore is reasonably priced except the HazMat shipping charges to San Diego are very high and add a couple of hundred to the price of the product. From the density published, I'm guessing it is about 40% poly and 60% ceramic. If I buy the same stuff here, I save well over $350. I talked with a few resin suppliers who say quite a few people mix their own with good results, I'm hoping to get feedback from some of them. Regardless, if I do it, I'll publish the results (good or bad) for the benefit of others.

 

[gjmsd]

Re: Mixing my own transom pour

For the price of quality epoxy, you might be better off buying Nidacore, its half the cost of seacast. They'll send you a gal pail just to sample.

Even using epoxy, ceramic and chopped glass, I can save over $200 and get a stronger, more flexible core.

 

[gjmsd]

Re: Mixing my own transom pour

Tried mixing a test batch of core material and so far looks good. I'm going to cut it into strips so I can test it for flexibility and check for voids. I mixed equal (by volume) parts epoxy resin, ceramic micro spheres and 1/2" chopped glass. The final hardened concoction is in the 7lbs per gallon range (float well in water). The exotherm wasn't bad but it was a reasonably small batch (1" thick).

 

[spunkymonky]

Bumping an ancient thread to see if anyone can contribute any more to this. I'm thinking of trying this or using a 20lb pourable rigid urethane foam in my transom.

 

[GA_Boater]

Bumping an ancient thread to see if anyone can contribute any more to this. I'm thinking of trying this or using a 20lb pourable rigid urethane foam in my transom.

Ya bumped it right to closure.