Mast ring for mounting blocks

[nestorph]

I have an Islander 30 with a keel-stepped mast. I need to add some blocks around it to accommodate various lines (halyard, reef, etc. the usual suspects). I'd rather not mount the blocks through the deck and I'm not crazy about using the mast itself. While I found a plate (see pic) that would do the trick, unfortunately it's designed to be placed under the mast. Is anyone aware of a manufacturer who makes a ring with holes that I could mount around the outside of the mast? Or perhaps someone has another workaround?
Thanks
Nestor

 

[Nereussailor]

I think that no matter what you do, you are going to have to drill some holes in the deck. You could have something made that would attach to the mast, but it might compromise the strength of the mast. I would think that the plate in the picture could be modified to work by cutting an opening for the mast to fit if it leaves a couple of inches all the way around. Just make sure that there are enough holes to properly hold it to the deck and that there is a good backing plate on the backside since the load of a deck stepped mast isn't there to hold it down, and seal it up really good. The Islanders were pretty solid boats. I don't see why this wouldn't work

 

[alexco38]

I dont think you should mount the blocks, called turning blocks, on the deck for a keel stepped boat. Because the block is going to lift the deck up around the mast.

You have to transmit the force to the mast.

You could make a plate and rivet around the mast with welded rings for mounting blocks.

 

[nestorph]

I know I'll have to drill some holes to attach the collar (I learned the correct term in my Internet meanderings) but I wanted to keep those to a minimum. And good advice about the backing plate. I thought about cutting out a hole in the center of that plate but the plate itself is too small. Another ideal requirement would be the ability to install it around the mast without unstepping it. The attached pic shows a model that won't win any beauty contests but certainly looks functional.

 

[alexco38]

Imagine all the line are tightly winched down. Each does about say 200lb. For norminal set of 3, there will be 600 lb lifting the deck up off you boat.

The force will be pushing down on your mast to the keel and lifting the deck. There is nothing to transmit the force from the deck to the keel. Good way to make more headroom.

Good luck

 

[nestorph]

LOL--love the headroom remark. I see your point. I'm now more inclined to go with the mast approach. I've seen examples where the blocks are hooked to straps that have been bolted onto the mast. That means that the forces are tugging on the two screws securing the strap in a shearing fashion. Do you think your suggestion of a plate riveted to the mast would distribute the pressure more evenly?

Imagine all the line are tightly winched down. Each does about say 200lb. For norminal set of 3, there will be 600 lb lifting the deck up off you boat.

The force will be pushing down on your mast to the keel and lifting the deck. There is nothing to transmit the force from the deck to the keel. Good way to make more headroom.

Good luck

 

[Davidasailor26]

I dont think you should mount the blocks, called turning blocks, on the deck for a keel stepped boat. Because the block is going to lift the deck up around the mast.

You have to transmit the force to the mast.

You could make a plate and rivet around the mast with welded rings for mounting blocks.

Our boat has a keel stepped mast, but where the mast passes through the deck it has a pin that rests on a collar attached to the deck. That pin prevents the deck from lifting. The collar has the boom vang attached to it, and has unused tangs for other accessories.

 

[Nereussailor]

I like the idea of a plate secured to the mast except the thought of putting a bunch of holes in the mast at a point where the mast is most likely to break. I do have a question for Davidasailor26. Does the pin go all the way through the mast, or is it just welded to each side?

 

[Davidasailor26]

I do have a question for Davidasailor26. Does the pin go all the way through the mast, or is it just welded to each side?

The pin (about 1/2" stainless) goes all the way through the mast. The owners manual states not to sail without it in significant winds to prevent deck lifting (only an issue on first commissioning).

 

[Davidasailor26]

The collar on ours is part NG46-10PH on http://www.rigrite.com/Spars/Isomat_Spars/Isomat_Masts/NG46_mast.html. They don't seem to list the pin but they do say O'Day (our manufacturer) uses a 1/2" pin.

 

[Barnacle Bill]

There are a number of blocks available to turn halyards and lines away from the mast and they can be installed on the mast as well. Look at Schaefer's Halyard Lift Blocks as an example. Harken and most hardware manufacturers have similar products. And, if you have internal halyards you can either use exit boxes or exit plates (or just well cut slots) out of your mast up higher where the lines exit and then go through the halyard lift blocks. You should stagger the exit holes, however so you don't compromise the mast strength.

 

[nestorph]

Well, this is embarrassing. I "misspoke" (miswrote?) in my original posting. Turns out I have a deck-stepped mast, not keel stepped. Does this change any of the opinions on the relative merits of deck-mounted vs. mast-mounted blocks? The various halyard lift blocks that I've seen advertised appear to be specifically designed to attach to the deck. I used similar ones on my previous boat but never really did any proper research into the pros and cons. I'd like to do it right this time.

 

[Nereussailor]

Yes it does. Remove the mast base put a plate like the ones you show under it replace mast base and you're good to go.

 

[Blitz]

Give Garhaurer a call. They made me a plate a few years ago since my mast was keel stepped. They have various ones also on website but most likely will need to be custom made. I'm very pleased with mine.