Cast Iron Keel

[barnakiel]

Originally Posted by PAR

... Barnie, without a full dissertation of common epoxy formulations, you will be helpless to fully understand the typical combinations of materials ...

... The 10 times factor if of the reinforcements used in both pre-thickened epoxies and primers (paint). Shredded cotton is a common reinforcement used in textured, hard coatings (some paints or as a fillet material in epoxy). Yep, that's right shredded bits of tee shirts. How much do you think a cup full of shredded tee shirts cost? How much do you think you pay for this material, when it's used in epoxy or a paint?

I would not jump to conclusions. Some sailors ARE educated in boat building even though they might be posting on a cruising forum.

If you say International adds shredded T-shirts to epoxy then you probably say what you know but this information is not contained in product datasheets which I read. I cannot tell you what they add, but they claim to add i.a. rust inhibitors.

I think the 10-times factor simply is not correct as much as your reasoning is correct. The factor is there, just maybe it is not 10.

I too think large custom support blocks would be difficult but then again they are still a nice option for someone whose boat goes always to the same boatyard. Some boatyards will store small quantities of sailors stuff esp. those that cater for the local sailor.

barnie

[PAR]

Barnie, I seem to continuously be restating what has been previously mentioned, but possibly misunderstood.

Never in the above post, did I suggest shredded tee shirts was used in the Interlux products you mentioned. I did say that this is a common filler material in hard coatings, which primer wouldn't and shouldn't be confused with, at least I understandably assumed as much.

The 10 times factor is more then accurate, in fact some materials added are well above this value. Just because you don't understand the formulation, doesn't invalidate the reality of the formulation, it just means you don't understand the cost of the materials used, when purchased separately, compared to costs of the same materials, mixed into another product.

Many yards will use high density foam to form custom keel blocks. These are kept in a shed or locker and are boat specific.

[Skylark]

No matter what you use, over time there will be rust pimples and streaks that need to be recovered. In 2002 I spent days chipping off a failed epoxy coating (cracks and rust underneath the epoxy) and applied POR15. I believe the first coat was a metal primer of some kind. Every year there are a few bubbles and pimples that get rustoleum rust converter covered with bottom paint. There are no serious rust areas, just a few small areas that get hit every year. Epoxy may get you 10 years, but then it is a big job to remove. I would rather just touch up every year than go through that again.