Expandable Foam as Mast Wedge

[osirissail]

- - Definitely do not use expandable foam. Both UV and/or just high temperatures will cause shrinking and degradation. You mast will be flopping around in a year or two or less.
- - Spartite is 2-part RTV rubber at an extreme price. You can purchase pint/quart/gallon cans at WWW Grainger & Co in the USA. You will need a friend with a business to purchase it as WWW Grainger is a wholesaler. The price is a fraction of the Spartite price.
- - You install a "dam or barrier" underneath the deck around the mast. Then mix up the two part RTV rubber and pour it in the cavity around the mast.
- - RTV rubber is used to make molds for metal parts in industry. It hardens but can be bent enough to extract the molded piece. As a mast wedge it works great. It can move a very little bit so that shock loads to the mast don't buckle the cabin top. I installed it around my two mast 10 years ago and it is still in good shape. However as the boat and mast flex it will loose it grip on the painted aluminum mast and you will need a mast boot to keep water from working down the surface of the masts and into the boat.

[Stillraining]

I Would be interested in a link for that..I have been all over Grangers web site and cant find it.

How ever if it is the same mold rubber used in some of the on line videos..its not the same stuff as Spartite...Spartite is all but impossible to cut without a saw...it is really not flexible at all in the sense of the term...it cures very hard...you can not get a finger nail into it.

FWIW... it is designed to stay on your mast when you unstep and acts like a aligning dowel when resteping..therefor your partners need to be tapered and very smooth to allow for this lifting out...I am having mine rebuilt in this fashion as we speak just for the spartite application...with a 5 to 7 degree taper.

You can go ahead and use it if your partners are not set up for it but you may end up having to run a long bladed sawzall around the mast a 1/2" away or so to get it out without ripping your deck up. That's what i was going to do...but since the yard laid my mast over in my boat for me I get to order the repair now to my specifications...a small silver lining to the mishap if there is to be one I guess..

[sestina]

I wouldn't touch that Spartite stuff. Having seen a 80' cutter being lifted up by it's mast as the crane tried to unstep the rig.

The riggers took two days to chisel and drill the stuff out, chewing up the mast pretty well during the process.

I'll stick to rubber wedges and a hypalon boot.

[Squeaks]

I just installed Spartite for my rebuilt keel-stepped mast and yes, it's expensive. The istructions say to coat the inside of the partner (and mast too if concerned about removal) with Vasaline. Seems like a better alternative to wedges.

[Christian Van H]

Here ya go my friend: Smooth-On - Mold Making and Casting Materials for a World of Applications! Make your own spartite! You can use Gords posted specs to get a urethane or another two part rubber relatively cheap there...Chris

BTW, try to find one that is a 1:1 mix using volume, and their spray release agent works really well...

[Stillraining]

Thanks Christian...I already purchased my Spartite last year and its been sitting in my office but now I know of an alternative.

Yep... vasoline is the ticket around the partners..but as I said they have to be smooth as well..I want mine sticking to the mast..just not the partners..That was one stout deck to handle that load and one dumb crane operator IMHO..

[osirissail]

In my boat business I would buy 55 gal drums of this and that and repackage it down to smaller sizes needed by sailors doing their own work. I could charge half the price seen in boat store chains and still make a 1000% on the item. I was using molding RTV before Spartite got the same idea and repackaged commercially available molding rubber same as what I was doing. They made a good business of it and offer a product in "small quantities" convenient to the individual sailor. You can get really good prices if you buy a 55 gal drum of the stuff - but will you do with the leftover 54.5 gallons?
- - There are about a dozen different "grades" of molding RTV rubber varying from really flexible to really stiff. I do not like the "really stiff" for the reasons posted by others above. I like one grade softer so that the material can absorb some of the vibrations and shock loads instead of transmitting them to the cabin top. Most cabin tops are simply a cored sandwich of FRG and it does not accept shock loads gracefully. Also a little more flexibility keeps the adhesion to the mast and cabin top intact longer.

[bewitched]

I can also recommend Spartite - yes expensive, but after 5 years and 3 mast pulls it is still working well & 100% waterproof (my pullman berth wraps around 2 sides of the mast and there has never been so much as a drop coming through).

Wedges in my experience work loose - especially in a big sea (when you really don't want to by trying to put them back!!).

Foam - not heard of anyone using it - but can't imagine that it would stand up to the fressures exerted from the mast flexing.

If you aren't prepared to pay the Spartite price, I would look into materials that retain their compressive strength over time and do not fully harden (Spartite retains a certain amounth of flexibility - like a hard engine mout rubber).

And don't forget to grease when re-stapping the mast!!!

[bewitched]

Originally Posted by sestina

I wouldn't touch that Spartite stuff. Having seen a 80' cutter being lifted up by it's mast as the crane tried to unstep the rig.

The riggers took two days to chisel and drill the stuff out, chewing up the mast pretty well during the process.

I'll stick to rubber wedges and a hypalon boot.

Sestina - sound very much like workmanship problem - either no grease / vasaline at spartite / deck interface or Spartite resevoir around mast was not correctly shaped.

I've pulled my mast 3 times and there has been very little resistance each time - and when the mast goes back in, there's no need for all that fiddly mast alignment work.

[Weyalan]

I used Spartite and was very happy with the results (previously used cedar wedges)

[barnakiel]

I believe the idea of the wedges is to keep it stiffly in front and from behind, and just waterproof at the sides - (no wedges at the sides, at least no stiff wedges).

The expandable stuff will crush and just fall out.

b.

[Pblais]

To me it seems idea, as the stuff form fits and is solid as a rock once cured.

There is a reason Spartite works. It's way more dense than expanded foam. You use expanding foam if it won't already move not for prevention of movement.

[sneuman]

Originally Posted by osirissail

In my boat business I would buy 55 gal drums of this and that and repackage it down to smaller sizes needed by sailors doing their own work. I could charge half the price seen in boat store chains and still make a 1000% on the item. I was using molding RTV before Spartite got the same idea and repackaged commercially available molding rubber same as what I was doing. They made a good business of it and offer a product in "small quantities" convenient to the individual sailor. You can get really good prices if you buy a 55 gal drum of the stuff - but will you do with the leftover 54.5 gallons?
- - There are about a dozen different "grades" of molding RTV rubber varying from really flexible to really stiff. I do not like the "really stiff" for the reasons posted by others above. I like one grade softer so that the material can absorb some of the vibrations and shock loads instead of transmitting them to the cabin top. Most cabin tops are simply a cored sandwich of FRG and it does not accept shock loads gracefully. Also a little more flexibility keeps the adhesion to the mast and cabin top intact longer.

Which grade do you recommend? I have been over both sites recommended here, but can't seem to get my head around what is needed.

[sneuman]

bump.

[osirissail]

You can find the different grades of RTV sold in the WW Grainger catalog and in other professional mold supplier catalogs. You must be a commercial enterprise to get access unless you have friend with a business account with WWG. Which is one reason Spartite makes big money - convenience of access to the retail paying folks.