Seacast: The Bottom Line

In Response...

What is the major difference between today's composite hulls made of the 1/4" fiberglass, foam material, 1/4" fiberglass construction and a full solid material like Seacast® :

• The difference is that Seacast® is based on the same material as the rest of the boat a the hull. Seacast® has a certain amount of resiliency, which keeps it from cracking. In seventeen years we have never had a cracked or broken transom. Even with the enormous Hp hung on some transoms.
•*In contrast to foam, Seacast® is not friable - so the bond is superior. Seacast® has been tested by a dropping 20 lb weight, from a height of 10 ft, on a 6" wide 1.5” thick piece of transom - did not break after 200 repeats. In comparison, a standard plywood transom is destroyed after one drop and all other materials tested failed after the third drop.
• As to the question of bonding to wood. Yes, it bonds very well, BUT you must remember the wood itself will be the “weak link”.

Flexural Test Results
• Structural Composites, Inc. tested Seacast® against marine plywood.

Panels Flex Strength Flex Modulus Max Load Catalyst

Seacast® A 17290 psi 903762 psi 6053 lb MEKP
laminate
Seacast® B 17641 psi 845039 psi 6443 lb BPO
laminate
21 Ply hardwood 10204 psi 1005342 psi 3598 lb

All other tests results will be on our new website soon.

 

Seacast Made a Believer ( So Far )

Guys, I don't know what all of the fuss with seacast is about. I called and talked to a representative at Seagull of Volusia on February 10th to request some written information and a sample of their seacast product. I recieved the seacast sample and the step by step guidelines for its use on February 15th. That is only 3 working days. I find that to be excellent customer service. The product sample that I recieved was a small piece measuring 1.5" thick and approximately 3" in width by 1/2" in thickness. From what I can see this seacast is very strong and adherses very well to "Fiberglass". With reading all of the information sheet and the website it clearly states that seacast is a filler compound to be sandwiched between fiberglass barriers. I'm a firm believer in the product now that I've actually had it in my hands. Seagull of Volusia, I say to you that I will be using the product in the very near future to pour a transom. If that goes off without a hitch then I do plan on using it to redo the stringers in the boat as well. Thanks again to Seagull for their wonderful customer service. You all obviously believe in your product.

 

Seacast

I have run a boatyard that has used the seacast to repair rotted stringers in a powerboat. I was not at all impressed with the application or the results. After "pouring" 4 stringers and letting them cure I was not satisfied with the results. There was an excessive amount of time prepping the existing skins in order for the seacast to properly adhear to the skins.The resulting "stringers" did not exhibit nearly the strength or rigidity I needed. I ended up replacing the stringers with wood glassed over.

 

par is right on with this, there is no way around doing it the right way and briefly that is to remove the rotted core from the inside leaving the outer skin and going with a synthetic or marine ply as your core material and using a traditional layup method with west system epoxy.

 

Seacast

Three years ago I was given an old Mark Twain. I gutted and redid the interior, and on the third weekend out the transom split. It was rotten. I looked at my options, trash a boat I just refurnished, spend 1500 on a transom repair, or try something else. I chose Seacast. Granted it took time to chainsaw out the old transom completely, but with prep, shipping, and curring, the process took me very little time on the whole, much less than replacing the transom the other way. The Seacast was easy to pour, and the transom came out perfect, in fact, much stronger than the original ever was. That was three years ago, and it has been tested many times since. Total Cost $350. I will recommend and support Seacast as long as its around. The product saved me soo much time, work, and money. I don't know about using it for floors or anything else, but it is the best for transoms.

 

UPDATE!!!!!

I made Seagull's month. I spent over $1500 on the stuff. what i did was not possible with any other (sane) rebuilding method. Main stringers all the way forward and transom are now FULLY COMPOSITE... no more balsa. all this without touching my deck and working only through access hatches. all my original gellcoat remained!! why rebuild with an inferior product when you can make it last forever... hmmmm... ok maybe just longer. if you can take the extra 200 lb penalty... seacast and epoxy all the way dudes!

THEN, i hung a 30" bracket and twin V6 HPDI's on the back. I've been pounding the boat for 3 years... zero signs of stress fatigue so far. Looks like it came like this from the factory.

screw west systems, call up mark at US composites and tell him to set you up with the his thin epoxy and some combo 45 deg mat.

WOOD SUCKS!

 

What you mean is BALSA sucks.

Quite a lot of discussion on that around these forums.

 

Foca, what you did was pour a liquid polyester, into dirty and contaminated stringer cavities. Polyester requires a mechanical bond in this application, which you can't get without exposing the previous core areas and grinding them with a very aggressive grit.

In short, you now have stringer tubes full of a material that doesn't offer longitudinal strength, but most importantly isn't well bonded with the laminate. For a cored structure to work as intended, the core and the laminate have to be well bonded. If they aren't the core will shear from the laminate and the two will act independently of each other, which isn't good.

I hope you have good luck with your choices, but I've repaired enough stringers and transoms to know for sure, that there's no miracle goo in a can going to save the day.

 

hmmm, NO, i mean ALL WOOD sucks. my transom wasn't balsa, and most aren't. They rot too.

i work for a company that makes helicopters. One of our helicopters has wood in it... it was designed in 1950.

today, entire production aircraft are composite... like it's always been in the past, aerospace technology eventually works it's way down to other industries.

the only reason only SOME manufacturers have switched to NO-WOOD construction is simple: COST.

composites take more knowledge, design work, technical skill, and of course cost more in material. They have come a long way in the last couple decades. wood is outdated. period. If you want to cut cost and you can totally encapsulate it (not a SINGLE hole through the glass), then it is merely ACCEPTABLE.

this is starting to sound like the old carbeurated vs EFI discussion, those guys thought old technology was better too back then, but there is not too many of those dudes left today. yeah, columbus did the atlantic in a wood boat. means nothing now, it's time to move on.

it's been done... it only takes money. intrepid has had wood-free models since the early 80's... they're still not rotten.

 

PAR,

there is a SOLID mechanical bond. it was scratched and cleaned COMPLETELY before the pour. Before doing anything i took samples of the existing glass and did bench tests for bonding to be sure. trust me, it is more solid than if i was trying to bond to wood. if you did a tensile strength test, you'd have to pull harder to get the glass off of the seacast.

since we are talking shear though, I have seen no evidence of problems YET. not through bench testing and not in the boat application. I took the tank lid off and inspected the two main stringers a couple months ago, no signs of delamination.

Bear in mind however, this boat was also structurally enforced with Epoxy layups after all the poly work was completed. there are more loads now with the bracket and twins, but the load paths have been looked at and reinforced (that may be better OR worse for the seacast bond... we'll see).

SO FAR, i have complete confidence. Tried and true is great, but it didn't get us to the moon. If we have better tools today, why not use them. I think the risk is minimal at this point, as long as you are smart about it.

 

Two of the testimonials look fishy. Foca, you just have no idea of what you are talking. Good luck with your "flexible flyer"!

 

"fishy"...OK.

good luck with your rotten (or rotting) boat(s).

 

Update

LOL. I crack up everytime i read this thread. good logbook of where i was a few years ago. Too FUNNY. and the responses! it's awesome. Gotta love the forums.

I've done a lot more composite work since. Now, it's pretty much a go to material for me, including the adhesives. Much like auto and aerospace companies, I even use it to bond metal to metal, if i don't want to weld or steel-to-aluminum.

I actually ran into a guy in Riviera Beach. Matt of Target boats. He refurbs old boats and only puts composite in. I think he uses Coosa Board for transoms and has molds for hollow stringers. really does INCREDIBLE work. look him up if you are interested in updating your old boat. He ain't cheap, but one of the best I have ever seen.

*******UPDATE**********
The boat is still running great! Sees the bahamas at least once or twice per year. Most problems with it have been related to the Yamaha HPDI's and the ethanol switch. Think all that is sorted out now.

SO, AS OF 2012, NO DELAMINATION, CRACKING, OR ANY KIND OF FAILURES. The boat is run through 2-4' seas regularly, and it has been through 4-6' (unfortunately). It's ridden pretty hard, has a ton of power and fuel economy is incredible. over 2 miles per gallon.

As pointed out above, PREP IS KEY. Don't forget, any time you use an adhesive (like paint) surface prep is EVERYTHING.

 

great to hear the boat is holding up well. the only question i have is how hot did the seacast get when you poured it. i have just done a similar job with polyester and chopped matt on a little runabout i have. i poured the resin in one liter batches and it got bloody hot, had to sponge the transom with water while it set. it has turned out really good and only took a day. normally i do the normal wood replacement but i had a heap of resin sitting there and thought i would give it a go. glad i did.

 

it definitely got pretty hot. we had a temp gun on it, and made sure it was acceptable, within wolfgang's recommended limits at least. The SeaCast was being used per "design", thick pour. Pretty sure he can fill you in on tests they've done on this.

as far as exotherming other "glues", i'd say you need to be careful. Tests would be a good idea. there is a max temp befor bad stuff happens (weakening/cracking), can't remember off the top of my head. When we were laying up roving with epoxy, we did some tests on how many layers deep we could go, so we knew we weren't up against a limit.

oh wait, I think i remember about 4 layers of .036" combo. or something like that. don't bank on my memory, do your own tests to be sure...