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Old 30-11-2009, 17:59   #1
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Looking for Pics / Ideas of Mast / Mastbase Brackets for Halyard Blocks

Hi folks,

My mast is deck-stepped with an aluminum step.

I installed new rope clutches on the cabin top, and deck organizers last year, but am still kinda "micky mouse" with a few blocks, of different makes / designs / shackles attached to either side of the mast (at various heights) to get my halyards, and reef lines to run up to the organizers.

I would like to buy or make (Have welder, scrap stainless, and rods) some type of bracket to bolt around the mast, or to the deck, to hold the blocks. I would prefer to have it on the mast, as I would not have to worry about bolting it to the deck, backing plates, keeping the water out, etc. However, I am open to all input!

I have seen a few in pics before, but google doesn't bring any good pics up, and searching here brings up alot of irrelevant threads. I may not have the right terminology - mastbase brackets, etc.

Here's a pic of the deck / mast step before I added the organizers and clutches.
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Old 02-12-2009, 21:48   #2
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It looks like the boat's mast is "deck stepped" Yes? No? If deck-stepped then a plate underneath the mast "shoe" will be where you attach all your blocks for lines running up the mast. Avoid drilling holes into the mast as that sets up weak spots and promotes cracks forming in the mast tube. Most mast shoes for deck stepped masts have attachment points for the various sheaves for your running rigging. If yours does not then have a thick stainless plate made that will go completely underneath the existing shoe and attach your sheaves to that plate.
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Old 03-12-2009, 00:09   #3
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How about this? This one goes around the mast but the same concept.
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Old 03-12-2009, 06:36   #4
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Looking closely at Northeaster's photo - it is evident that there is a deck-stepped mast shoe on the cabin top.
Where is the mast?
Does the mast have winches mounted directly on the mast?
Are you converting the running rigging from mast mounted winches to cockpit mounted winches?
Is this a hurricane-damaged boat and does not have a mast anymore?
- - In converting from on mast winches to cockpit winches any lines coming down the mast from the mast head or from the gooseneck of the boom have blocks installed at the base of the mast or cabin top level. How this is done is different on keel-stepped masts versus deck-stepped masts. The principle involved is that any line coming down the mast will put an upward pull when it makes the right angle turn at the mast/cabin top. Blocks must be installed so that the pull is borne by the mast tube and not the cabin top. With deck stepped that is easily solved by a plate mounted underneath the mast shoe. With keel stepped masts you need a system that "captures" the mast tube and transfers that upward pull of the lines directly to the mast tube and not to the cabin top.
- - The photo shows a mast shoe on the cabin top so all you need is a stainless flat thick plate under the mast shoe shaped with "ears" that extend outward and upward from the mast shoe. 45 degrees or 60 degrees upward bend will work. Holes are properly drilled in the plate for the mounting the sheaves. Smaller rigs use a "square U-shaped" plate like the profile of channel iron. The plate needs to be also drilled to allow the mast shoe mounting bolts to pass through to the "in cabin" compression post for the mast. You might need longer bolts to accommodate the added thickness of the plate.
- - On deck stepped masts you do not want to put a "collar" around the base of the mast or drill into the mast. Doing so will introduce stress into the mast tube right at the mast shoe area which can result in "pressure-induced welding of the mast tube to the mast shoe resulting in not being able to remove the mast. Drilling holes sets you up with "perforations" around the mast where stress cracks and mast failure is promoted. Any holes drilled in a mast are potential failure points so should be minimized. Removing mast mounted winches leaves open holes into the mast tube which should be properly welded closed to avoid water entering the mast tube and to restore the continuity of the mast tube.
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Old 03-12-2009, 08:50   #5
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Garhauer Marine Hardware -442033
Garhauer makes a number of base plates for deck stepped masts. They will also do custom work if their stock plates don't work for you.
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Old 03-12-2009, 16:14   #6
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Thanks for all of the great info.

Delmarrey - I really like the look of yours, but where mine is deck stepped, I will follow the advice of Osirissail, and try to install a plate under the deck.

I will measure the mast /boot, and see if any of the Garhauers will fit. I have never removed the mast boot before, so I wil have to see how easily it comes out.

It is not a hurricane damaged boat or anything like that, and yes, it is deck stepped.

There are two mast winches that I don't use, as I have all lines lead back to the cockpit. The boat came with the ability to have 3 lines lead back, and I have increased that to 7, by moving the cabintop winches aft, and installing rope clutches, on each side (one triple, one quad) ahead of the winches.

As mentioned in the original post, I already installed deck organizers as well, on each side, and everything worked fine. The only thing that I would like to improve upon, is the way that all of the blocks are currently scattered / attached at various heights from 1 - 2' off the deck, to existing padeyes on either side of the mast.

One thing that I like about Delmarrey's setup is the use of fixed blocks, rather than loose blocks shackled to attachement points on a plate.

If the lines ate taught, it is not an issue. But, for reef lines ( I have 4 in total) that are slack until the sail is raised, I find that the loose blocks tend to get fliiped around, or tangled sometimes in the line, as the sail is being raised. Not a huge issue though, but the fixed blocks may be better for this??
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Old 03-12-2009, 18:46   #7
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The use of the fixed turning blocks like in Delmarrey's photos is elegant looking, but requires a larger base plate under the mast. That plate is then subject to being warped upwards away from the surface of the cabin top. If the plate is bolted through the cabin top then you are back to the situation where you are "lifting" the cabin top when you tighten your halyards and other running rigging. This "lifting of the cabin top will induce cracks and fractures in the cabin top as the mast is pulled down by the lines and the cabin top is pulled up by the turning blocks.
- - The plate that is mounted underneath the mast shoe and on top of the cabin top needs to be small enough to transfer the upward "pull" to the mast tube. That is why the Garhauer link in "Roverhi" shows the plates being small and "hugging" the mast tube. You use simple blocks that are attached to the holes in the plate. You can use single, double and triple blocks as necessary to bring the lines down the mast and turn then towards your deck organizer blocks. The "flipped" blocks that have slack lines can be avoided by using double or triple block where at least one of the lines is taught. Otherwise you just live with the "flopping" blocks. Damaging the cabin top is much more severe problem as when it cracks water will migrate into the coring and even into the interior of the cabin.
- - The underside of the mast boot is bedded in T5200 then through bolted to the compression post inside the cabin. It will take some time and long knives and chisel type wedges to ease up the mast boot and slice away the T5200 bedding material - If the T5200 bedding material was properly applied. If the mast boot comes off easily from the bedding material then it was not properly cleaned before the mast boot was installed. You will need to clean the base plate and mast boot bottom surfaces very well and use acetone to insure no oil or dirt is present before putting new T5200 bedding and re-installing the new plate and the old mast boot.
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Old 03-12-2009, 20:09   #8
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Here's my Garhauer plate, with an added hole for a keel stepped mast...
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Old 03-12-2009, 20:26   #9
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Catalina Direct also has a selection of mast step halyard plates.
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Old 03-12-2009, 20:28   #10
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Catalina Yachts now feature Garhauer hardware...
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Old 03-12-2009, 20:32   #11
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osirissail is right on to a point with his statements but mine has had this set up for 30 years but I did install the base plate 4 years ago. And it is thru bolted and it is as big as it is due to the angle of the blocks to accommodate the organizers. You'll notice there is a large backing plate on the interior as well.

Also the deck is held down with a rod stay attached between the deck-boot-plate and the deck collar. This aids in stabilizing the the rise in the deck. You can see it coming down from the deck in the interior picture. I have been considering installing a interior arch that goes between the two chain plates that is attached to the deck.

If I heal over more then 35 the leeward shrouds go slack, which means my deck is rising and squeezing the hull. BUT, after 30 years it doesn't seem to have done any damage. Boats are meant to flex some or they would crack.

The blocks (Schaefer halfmoon blocks) are held up with internal springs which will not flop over but are allowed to rock side to side.



As for crushing the mast base into the deck collar I think he is little over zealous in his statement. e.g Hydraulic back stays can put a tremendous load on a mast. I can bend my mast so much it seem scary but no failure or "pressure-induced welding" as he's stated.

But yeah, I would put the base plate under the deck collar but I'd still attach it to the deck. The reason the blocks are so close to the mast is so they don't wear on the mast halyard exit plates.



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Old 03-12-2009, 21:02   #12
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Del...Just to be clear...I have to differ with you regarding your leeward shrouds coment...All boats should ease shroud tension on the leeward side...it is the sign of a properly tuned rig..It has nothing to do with deck flexing...not that yours might be as well.
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Old 03-12-2009, 22:58   #13
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S R - The only time the lees go slack is when I have too much canvas up for the wind conditions. I keep a Loos gauge on board and check them every spring. I have 3/8 wire P/S w/ 7/16 fore & aft so I doubt that the wire could be stretching on a 15K # boat. So the only thing I can contribute it to would be the hull flexing/squeezing.

It only happened when I got caught in a couple good gusts w/ old sails, over by the cliffs at Oak Harbor, when I first owned the boat. I don't allow anymore then 25 now. It's just a waste of energy and the shrouds alway stay straight. Besides the vessel sails fastest at 20
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Old 04-12-2009, 05:26   #14
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The rod "delmarrey" is mentioning is known as an "anti-pumping" rod. It is installed to minimize the "pumping" up and down of the cabin top. As it is attached to the bottom of the mast down at the keel mast shoe it transfers the "pulling" of the halyards/lines from the cabin top to the base of the mast.
- - One way to determine if you are getting any cabin top "pumping" is to temporarily tape or strap a rigid rod to the front or aft side of the mast above the cabin top boot so that the bottom of the rod is touching the cabin top. Make a mark with another piece of tape at the top end of the temporary rod. Make sure the rod can move but with enough resistance that it will stay up if the cabin top is moving. If the cabin top is "pumping" it will push the rod up the mast while sailing in moderate or more winds and seas. After you return you can check to see if the rod has been pushed upwards by the cabin top.
- - If that is happening, PM me and I will send you a simple (sort of) fix that involves a clamping collar on the mast above the cabin top boot plate.
- - As to "tuning" the rig/shrouds, there is a calculated tension for each size boat determined by mast size, displacement and shroud length, etc. This is the "at the dock" tension of the shrouds and stays. At sea under moderate conditions it is normal for the lee shroud to "unload"/go slightly slack, but it should not be "flopping" around. If it is, then either the shrouds have stretched and need tightening; or the hull is "canoeing"; or the mast itself is bending out of column to leeward which is a much more serious problem. That is normally caused by improper initial measurements of port and starboard shroud lengths before the "at dock" pre-loading of the shrouds.
- - If the pre-load "at the dock" tension is excessive/too much then the mast will adopt a slight "S" shape which underway will effective shorten the mast height and really unload the lee shroud. This situation is shortly followed by the mast breaking into two or more parts.
- - Normally inside the cabin there is a transverse bulkhead located at or near the mast that prevents the hull walls from canoeing. The old wooden boats had a massive ceiling beam in that location to do the same thing. Modern FRG boats sometimes separate the port and starboard sections of this transverse bulkhead to allow full headroom for people to go forward to the V-berth or whatever. The problem is then that the anti-canoeing structure is then transferred to the cabin top and the use of a proper "anti-pumping" rod is critical.
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Old 04-12-2009, 07:55   #15
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I don't mean to hijack this thread but just respond............

Quote:
Originally Posted by osirissail View Post
The rod "delmarrey" is mentioning is known as an "anti-pumping" rod. It is installed to minimize the "pumping" up and down of the cabin top. As it is attached to the bottom of the mast down at the keel mast shoe it transfers the "pulling" of the halyards/lines from the cabin top to the base of the mast.
- - One way to determine if you are getting any cabin top "pumping" is to temporarily tape or strap a rigid rod to the front or aft side of the mast above the cabin top boot so that the bottom of the rod is touching the cabin top. Make a mark with another piece of tape at the top end of the temporary rod. Make sure the rod can move but with enough resistance that it will stay up if the cabin top is moving. If the cabin top is "pumping" it will push the rod up the mast while sailing in moderate or more winds and seas. After you return you can check to see if the rod has been pushed upwards by the cabin top.
- - If that is happening, PM me and I will send you a simple (sort of) fix that involves a clamping collar on the mast above the cabin top boot plate.

Actually I've have marked the overlap on the mast boot and have seem as much as 1/2" of movement but I don't think that's enough to worry about as long as I keep her canvas under control.

- - As to "tuning" the rig/shrouds, there is a calculated tension for each size boat determined by mast size, displacement and shroud length, etc. This is the "at the dock" tension of the shrouds and stays. At sea under moderate conditions it is normal for the lee shroud to "unload"/go slightly slack, but it should not be "flopping" around. If it is, then either the shrouds have stretched and need tightening; or the hull is "canoeing"; or the mast itself is bending out of column to leeward which is a much more serious problem. That is normally caused by improper initial measurements of port and starboard shroud lengths before the "at dock" pre-loading of the shrouds.

The only time I ever had any flopping slack was that time mentioned above and the shrouds have been adjusted with a Loos gauge according to their specs. As far as the boats specs, good luck on finding that.

- - If the pre-load "at the dock" tension is excessive/too much then the mast will adopt a slight "S" shape which underway will effective shorten the mast height and really unload the lee shroud. This situation is shortly followed by the mast breaking into two or more parts.

As for the mast' it's straight up w/o any tension and as I tighten up the hyd. back stay it turns to a nice arch.

- - Normally inside the cabin there is a transverse bulkhead located at or near the mast that prevents the hull walls from canoeing. The old wooden boats had a massive ceiling beam in that location to do the same thing. Modern FRG boats sometimes separate the port and starboard sections of this transverse bulkhead to allow full headroom for people to go forward to the V-berth or whatever. The problem is then that the anti-canoeing structure is then transferred to the cabin top and the use of a proper "anti-pumping" rod is critical.
The bulkhead is about 1-1/2' forward of the mast and chain plates and is attached 360. I haven't seen any stress marks so it must be doing its job.

This boat is completely cored through out so I believe there to be a fair amount of flex but it's held OK up for 30 year, 20 years of which was in the race circuit, so I've accepted its attitude.

And thanks for your input ......................_/)
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