Sealants and halyards...

[blueranger]

Hi,

In the Sensible Cruising thread, members SD, Halekai36 and Cam all express reservations about using 5200 and silicone. I need to install a thru-deck fitting to run the cable from my VHF antenna from the mast down into the cabin. What sealant would be best?


One other slight problem. The masthead sheave for the main halyard is shot. The PO I think fixed this by just hanging a block in an open spot in the sheave. I found a brand new shackle for the mainsail but there is no rope to wire halyard running down the aft side of the mast.

Can I run a 3/8" halyard through the block and secure it with a bowline to the head of the sail with the shackle? The block is not a "V" so not meant to run wire unlike all the blocks in the masthead. I can cleat the halyard off in the cockpit once the mainsail is up.

I'm going to drop the mast and rewire it and put in a new masthead sheave in the Fall, I'd just like to get some time in on the water while there's still summer here.

Thanks,
Mike

[Quickstep192]

Having gotten my hands snagged by wire halyards, I'm not a fan. Also, I would suspect (but I'm not 100% sure) that high tech lines have made wire halyards all but extinct. As for attaching a shackle to your halyard with a bowline, the only problem I see is that the bowline/shackle combination might prevent the sail from going all the way up.

Here's my read on sealants:

5200 is for when you never ever want to take it apart again. There are solvents now that help get stuff apart, but it's overkill for most applications.

4200 is for when you want to get it apart again. I've used 4200 for thru hull fittings with perfect results and find it quite nearly as tenacious as 5200.

Silicone is for when you want it to come apart by itself

[sailingdog]

Polysulfide sealants are very good if you're bedding metal hardware, but not so good if bedding anything with plastic in it. Polysulfide adhesives tend to attack most common plastics.

4200 is a polyurethane-based sealant, and very good for 99% of the work you might be doing. I bedded the solar-powered vents, the new mast step, the Spinlock PX PowerCleats and Lewmar line clutches on my boat with 4200.

As for wire-to-rope halyards... get rid of them. T-900 and other high tech dyneema/spectra/vectran based lines are far gentler on the other hardware, like the mast, the sheaves, your fingers, and lighter as well. They're often stronger than the steel wire they're replacing as well. For instance, 6mm wire rope has a breaking strength of about 2900 lbs. 6mm t-900 spectra/polyester double braid line has a breaking strength of about 4400 lbs. Basically a no-brainer IMHO.

I don't recommend using a shackle and bowline. The bowline is a horrible knot for use with a shackle. You're much better off using a buntline hitch or something similar. They're easy to tie, difficult as hell to untie once they've been in a while and very compact. Here is the buntline hitch:



Get yourself some 5/16" or 3/8" Sta-SetX for your main halyard, since it is fairly low stretch, but much more reasonably priced than T-900.

[knothead]

Originally Posted by Quickstep192

Silicone is for when you want it to come apart by itself

I don't want to start up the whole sealant/caulking issue again, but I see and have to remove little dabs of plain old silicone that have been applied to the sharp ends of cotterpins and other items on rigging. (usually a better idea than taping IMO). Some of these dabs have been exposed to weather and sun for years and are amazingly resilient. I usually have to scrape or cut them off with my knife.
I can't remember every seeing it fall off by itself.

[bettyswollocks]

I too am in the process of replacing my wire halyard on my mainsail and had thought of using all rope instead. I was wondering what size though and what breaking strain ?
I was thinking 10mm 16 plait double braid polyester which has a BS of 2100kg. Will that be enough for a 36 Sloop ?

[knothead]

Originally Posted by sailingdog

I don't recommend using a shackle and bowline. The bowline is a horrible knot for use with a shackle. You're much better off using a buntline hitch or something similar. They're easy to tie, difficult as hell to untie once they've been in a while and very compact. Here is the buntline hitch:



Get yourself some 5/16" or 3/8" Sta-SetX for your main halyard, since it is fairly low stretch, but much more reasonably priced than T-900.

SD, What do you think about the halyard knot?

Attachment 1870

[knothead]

Originally Posted by bettyswollocks

I too am in the process of replacing my wire halyard on my mainsail and had thought of using all rope instead. I was wondering what size though and what breaking strain ?
I was thinking 10mm 16 plait double braid polyester which has a BS of 2100kg. Will that be enough for a 36 Sloop ?

Some of the factors that you might want to consider are the capacity of the sheaves, and rope clutches, (if you have them). And how you hoist the sail. Is it led to the cockpit?
If you usually haul the sail up most of the way by hand then you want to have a large enough diameter that you can grip it well. 3/8" is kinda small. I think that if you can go with 7/16' you might be happier.

[Maine Sail]

If the deck fitting is plastic use: Sikaflex 291 = 220psi or 3M 4200/UV4000 = 300psi

If the deck fitting is metal use 3M101 or Life Caulk = Both about 140 PSI adhesion

Here's a quick run down:

3M UV 4000 is a one part polyether with UV inhibitors added. It has a elongation before break of 800% and a tensile strength of 300 PSI.

3M 4200 is a one part polyurethane with NO UV inhibitors added. It has a elongation before break of 900% and a tensile strength of 300 PSI.

3M UV 4000 is basically, spec wise very similar to 4200 but because it is a polyether, and not a polyurethane, it reduces ti's elongation before break slightly (this should NOT be a concern).

3M 101 is a one part POLYSULFIDE! Polysulfides have a natural UV resistance and are the premier product for use in teak decks. Polyurethanes do not do well with UV so UV inhibitors are added. 3M 101 has a tensile strength of 139 PSI and an elongation before break of 416%.

Sikaflex 291 is also a one part polyurethane with lower adhesion than UV 4000 or 4200.. It offers an elongation at break of roughly 600% and is the easiest one part polyurethane sealant to get off in the future!

[MABON01]

I like to use the 3M 101 and 4000UV sealants. They work great and have never had any problems with them. As for the Halyards; most of the boats I've saild on in the 30 - 40' range run 1/2" rope. Rather than knots, how about splicing an eye to your Halyard shackle? It's not that hard to do.

[bubb2]

I use halyard knot on my boat for anytime I connecting a line to a shackle or other fittings. The only time I use a bowline is for jib sheets to the jib clew. The halyard knot looks so much cleaner in my opinion.

As for eye splices, I have tried and tried to splice double braid and it always looks like a snake that ate a camel.