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Following the refit of my 26' trimaran Im now in the process of setting a new system for the mast step. I'd like to convert into a raising/lowering systrem and rotating. I have seen plenty of different systems but wonder which is the most functional. (Please forgive my ignorance about rotating mast as I mostly sail in monohulls and out of few sails on a hobbie years ago I'm not familiar with this).

I've been checking on the one from the Seacart 26

1696266132_Seacart26.jpeg.a5035bdbf59bac7810670f537680f672.jpeg

And the one from the Cosair 760

 Corsair760.jpg.118adbb1f6a3348d505a0f48500b08f3.jpg

Both seems to be pretty similar but I wonder whetehr would make sense to build up something using bearings rather than the ball with hinged base like this:

2049427692_ROTATINGMASTBEARING1.jpg.90f8ceeac6c051ff724e0ebeb5293638.jpg1003961393_ROTATINGMASTBEARING2.jpeg.8a6ca130cf1a380ef59c073864c07e9b.jpeg1375223711_ROTATINGMAST_6.jpg.7fc07c934fe359340cd20e9c6c35d59f.jpg

 

 

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Look at what Farriers and Corsairs are doing.. it's nice and simple and works great.

I'd avoid using bearings.  A simple ball and socket with some tefgel once a season is what I use on my F28R.

Here's what a mast ball looks like.

https://www.colligomarine.com/products/farrier-rotating-mast-ball

For raising and lowering.. check out the farrier system.

 

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29 minutes ago, SCARECROW said:

The tolerences are too tight on a ball races bearing like that.  A bit of dried salt and it’s not going anywhere.

keep it simple, there is no need to re-invent this wheel.

it wasn't me, did read in someone post about the usage of plastic bearings instead...although I will follow the  your advise!

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5 hours ago, can-UK said:

Look at what Farriers and Corsairs are doing.. it's nice and simple and works great.

I'd avoid using bearings.  A simple ball and socket with some tefgel once a season is what I use on my F28R.

Here's what a mast ball looks like.

https://www.colligomarine.com/products/farrier-rotating-mast-ball

For raising and lowering.. check out the farrier system.

 

Thanks thats crystal clear for me. My doubts are regarding the socket in the mast should be sometrhing like this I guess:

1681576761_ROTATINGMAST_9.thumb.jpg.d4d83e33335ea629a86b848a829e6586.jpg

basically I female socket of those you sent me, right?

1658794892_ROTATINGMASTBALL1.jpg.86a89ee96a8647f316982753cb4ee7a7.jpg1567727186_ROTATINGMASTBALL2.png.a3dff30243a98a80c16d0e5310e5646f.png

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There's no cotter pin aft of ball on the 2 Corsairs, 96 & 01, I've owned.  The mast socket just falls onto the ball as the mast nears vertical.  Its kept together by gravity and stay tension.  Simple

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The back of the mast has holes in it that line up with brackets on the deck to allow the base of the mast to hinge/pivot without moving out of alignment.  This is only used when raising or lowering the mast. 

 

Screen Shot 2020-05-28 at 14.18.16.png

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thanks for the hint, its now cristal clear!

One last thing, does it make sense to fabricate this based on a trailer tow ball?stainless steel one, price is significatly lower than the original colligo marine the other fellow sent me the link ;-p

s-l1600.thumb.jpg.fb260e50d6aad653434030d52163dc7e.jpg

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If you can get a solid stainless or titanium towing ball, it should work. The chrome plating on a typical carbon steel towing ball will wear off,and then you will have a corrosion problem in a saltwater spray environment.

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9 hours ago, cyclone said:

Specify 316L stainless.

Yes - very important. The L is for low carbon, which retains its corrosion-inhibitive qualities better when welded.

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The reason ball bearings are not a good choice are also bending of the mast in a couple of directions. Ball bearings like loads to be radial in the plane of the bearing with some thrust loads acceptable. But they do not like a shaft or whatever bending in the bearing. The uneven loading wears 'em out.

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On 5/28/2020 at 9:05 AM, amgpuma said:

thanks for the hint, its now cristal clear!

One last thing, does it make sense to fabricate this based on a trailer tow ball?stainless steel one, price is significatly lower than the original colligo marine the other fellow sent me the link ;-p

s-l1600.thumb.jpg.fb260e50d6aad653434030d52163dc7e.jpg

My co-owner friend and I used exactly that for our Discovery20 (20ft trimaran) and it works fine so far.

We temporarily filler up the neck below the ball, packing taped it and molded the fiberglass "female" counterpart to the "male" ball hitch. So we ended up basically with a cylinder with a half sphere end. We then cut a slot on one side, the width of the neck. You can now bring the mast horizontal, push it against the ball, with the slot aligned with the neck and raise the mast.

I you need pictures let me know, I can get some.

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I did the same thing you describe for a 25' tri and it worked great. I have photos too, but I'd have to scan them (happened a while ago). The cup I made was carbon and thick-walled, made by wetting round patches over the ball and stretching Latex gloves over it for compaction. I did a few hits to achieve about 1/4" thickness. The slot worked well for raising and lowering.

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On 6/4/2020 at 3:14 PM, Russell Brown said:

I did the same thing you describe for a 25' tri and it worked great. I have photos too, but I'd have to scan them (happened a while ago). The cup I made was carbon and thick-walled, made by wetting round patches over the ball and stretching Latex gloves over it for compaction. I did a few hits to achieve about 1/4" thickness. The slot worked well for raising and lowering.

Would be great if you can send me few shots of the pics taken from your smartphone. Im curious about the deep of the socket itself. Many thanks

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On 6/2/2020 at 7:11 PM, Laurent said:

My co-owner friend and I used exactly that for our Discovery20 (20ft trimaran) and it works fine so far.

We temporarily filler up the neck below the ball, packing taped it and molded the fiberglass "female" counterpart to the "male" ball hitch. So we ended up basically with a cylinder with a half sphere end. We then cut a slot on one side, the width of the neck. You can now bring the mast horizontal, push it against the ball, with the slot aligned with the neck and raise the mast.

I you need pictures let me know, I can get some.

I was actually thinking to use the socket of the trailer as the female mold but not sure how to make the cast. If you are so kind to send few pics I would really appreciate it.

many thanks

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4 hours ago, amgpuma said:

I was actually thinking to use the socket of the trailer as the female mold but not sure how to make the cast. If you are so kind to send few pics I would really appreciate it.

many thanks

Laurent's co-owner here; some pics below.

So the goal was to make a simple and easy to use pivoting mast base to raise the mast with an A-frame. The old mast base sucked, it was a flat plate on a flat plate, I don't know who thought that was a good idea. Just didn't work. We trolled around for ideas and saw Russell's trailer hitch idea here and decided to run with that.

The old aluminum mast base casting was shot so we ordered a new one from Dwyer, used a bit of scrap marine plywood glassed heavily on both sides to make a plate the same size as the base, then drilled and tapped the mast base for two 3/8" aluminum studs. So the plywood plate can get bolted on to the mast base, so far so good. Next I had a bit of heavy fiberglass tubing which was 2 3/8"" ID, which gave us a little gap all the way around when the ball was in the tube. I cut off 2.5" of it and glassed onto the plywood plate. Then I put the plate on the bench with the tube facing up and rigged a way to suspend the ball in the tube with 1/4" or so of gap at the bottom and poured epoxy thickened with silica half way up the ball, so we had a female mold of the ball inside the bit of tube. Then I made a ball with a bit of 80 grit glued to it to open up the casting a bit to make the fit a bit more loose, and made a "fillet" by hand to transition from the casting to the rest of the tube.

Then we bolted the whole thing to the aluminum mast base with 4200 and nuts inside and out, then 4200 and 1/4" bolts to attach the base to the mast section.

Finally, we cut a notch in the back to fit the neck of the ball. So the mast is horizontal, you put the notch on the neck of the ball and crank on the A-frame. The mast goes up, pivots on the notch, and ends up with the ball in the cup, no extra pivot pins or anything needed. Dropping it is the reverse.

We've only raised the mast six or eight times so far, but it's been no drama at all. When sailing there's a bit of friction, probably need a teflon chip or something for friction in there to make it swing more freely, but even as it is all it takes is a bit of a pull on the rotation arm to turn it. Overall we're really happy with it.

ETDQ2wh.png

SpvsnJh.jpg

piwIkir.jpg

9WY9vzX.jpg

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5 hours ago, KONeill said:

Laurent's co-owner here; some pics below.

So the goal was to make a simple and easy to use pivoting mast base to raise the mast with an A-frame. The old mast base sucked, it was a flat plate on a flat plate, I don't know who thought that was a good idea. Just didn't work. We trolled around for ideas and saw Russell's trailer hitch idea here and decided to run with that.

The old aluminum mast base casting was shot so we ordered a new one from Dwyer, used a bit of scrap marine plywood glassed heavily on both sides to make a plate the same size as the base, then drilled and tapped the mast base for two 3/8" aluminum studs. So the plywood plate can get bolted on to the mast base, so far so good. Next I had a bit of heavy fiberglass tubing which was 2 3/8"" ID, which gave us a little gap all the way around when the ball was in the tube. I cut off 2.5" of it and glassed onto the plywood plate. Then I put the plate on the bench with the tube facing up and rigged a way to suspend the ball in the tube with 1/4" or so of gap at the bottom and poured epoxy thickened with silica half way up the ball, so we had a female mold of the ball inside the bit of tube. Then I made a ball with a bit of 80 grit glued to it to open up the casting a bit to make the fit a bit more loose, and made a "fillet" by hand to transition from the casting to the rest of the tube.

Then we bolted the whole thing to the aluminum mast base with 4200 and nuts inside and out, then 4200 and 1/4" bolts to attach the base to the mast section.

Finally, we cut a notch in the back to fit the neck of the ball. So the mast is horizontal, you put the notch on the neck of the ball and crank on the A-frame. The mast goes up, pivots on the notch, and ends up with the ball in the cup, no extra pivot pins or anything needed. Dropping it is the reverse.

We've only raised the mast six or eight times so far, but it's been no drama at all. When sailing there's a bit of friction, probably need a teflon chip or something for friction in there to make it swing more freely, but even as it is all it takes is a bit of a pull on the rotation arm to turn it. Overall we're really happy with it.

ETDQ2wh.png

SpvsnJh.jpg

piwIkir.jpg

9WY9vzX.jpg

Thanks a lot for such detailed report! This is one of the solutions I was thinking indeed The other one was to use a the trailer coupler foi r the tow ball, remove the handle and TIG weld a stainless steel plate which will fit in the mast base (oval shape) End of the day the coupler is done to support the max weight of the tow ball. I havent make the calculations though but considering my mast is heavier might need a 5'' base plus the 4 brackets for load spreading 

Trailer-Coupler-MArine-Grade-304-Stainless-Steel-C0265-0.jpg.222c56103f8512874905a0064fc49c6f.jpg

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It doesn't have to be huge like a trailer ball/socket.  My boat (19 footer, so your mast is bigger/heavier) uses a simple thimble/pin. Thimble is about the size of my index finger.

Thimble.jpg

socket.jpg

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You are right, it does not have to be as big as a trailer hitch ball for the mechanical load of a light multihull mast. But the advantage is that it is readily available (read "relatively cheap") and it acts as both the pivoting point once the mast is raised, and also the anchor point while the mast is raised.

The pin you have is enough to hold the mast once it is raised, but I do not see how it could be the anchor point of the mast while you raise it from horizontal to vertical. You must have something else to hold the foot of the mast while you raise it.

Many ways to skin a cat...

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It amazes me to see that the mast ball on a MOD 70 is only about 3" in diameter. I have looked for SS trailer hitch balls to use for a 50' catamaran mast ball but it seems that for road trailers they only go to 2-5/16" diameter but sometimes you can find a 2-5/8" ball but not in SS. I did find a French company that will mill or print about any size mast ball you want in SS or even Ti and even fit a load cell to it if one is willing to spend the bucks.

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32 minutes ago, Rasputin22 said:

It amazes me to see that the mast ball on a MOD 70 is only about 3" in diameter. I have looked for SS trailer hitch balls to use for a 50' catamaran mast ball but it seems that for road trailers they only go to 2-5/16" diameter but sometimes you can find a 2-5/8" ball but not in SS. I did find a French company that will mill or print about any size mast ball you want in SS or even Ti and even fit a load cell to it if one is willing to spend the bucks.

The one I got is in SS and 2'' outer diameter, 20 quids...good enough. The titanium one from colligo the other fellas show was over 100 bucks plus shipping....BOLA_1.thumb.jpg.50bf5f1aa1af2e048278632361309268.jpgBOLA_4.thumb.jpg.df9396c08ab088cac8f2de81748905f5.jpgBOLA_3.thumb.jpg.14e772a84f745af3aaa2d93da3cdf251.jpg

BOLA_2.jpg

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2 hours ago, Laurent said:

You are right, it does not have to be as big as a trailer hitch ball for the mechanical load of a light multihull mast. But the advantage is that it is readily available (read "relatively cheap") and it acts as both the pivoting point once the mast is raised, and also the anchor point while the mast is raised.

The pin you have is enough to hold the mast once it is raised, but I do not see how it could be the anchor point of the mast while you raise it from horizontal to vertical. You must have something else to hold the foot of the mast while you raise it.

Many ways to skin a cat...

You are correct, the mast rotates on a rod with a plate that is screwed into the base and the thimble just plops down onto the pin.  I do worry that if I ever capsized the mast may have sufficient slack in the shrouds to detach; so I'm trying not to capsize!!

They make hitch balls in sizes as small as 1 1/4" (mechanical sway bars); but 1 7/8 and 2 are most common for towing.  

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1 hour ago, Rasputin22 said:

Anyone know what the diameter of the Colligo Ti mast ball for the Corsair is? Not really a bad price in Ti it seems and a stable looking bolt pattern. 

I dont think it much smaller than 1.5'' and the weight saving is pointless, asuming the Ti is forged and the SS cast shouldnt be more than 200-300 grames?

 

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I'm going to see what sort of price Colligo will give me on a 3" diameter Ti ball. I think they may have their own mill now and possibly a laser sintered 3d Ti printer. I have a file they can print from.  Thanks Amgpuma.

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Trailer hitch balls are heavy as hell. if Colligo makes a titanium ball, it would be worth whatever they charge. I want one and I don't even need one! The G-32 step has to articulate sideways for righting, so I couldn't use a ball. I mocked the parts from wood and had them machined from aluminum with titanium pins. Works good!

 

DSCN4841.jpeg

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My tow ball SS is 750 grames while Ti is over a pound (475 grames) Thas not even the weight of a can o beer. Bending stiffness pre and post fatigue with such weight is also pointless for pourposses.

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  • 2 weeks later...

Amgpuma, tow ball is simple/good.  The G32 original worked fine.  You might consider a dyneema keeper line from the base to the spar, like windsurfers have at the tendon joint[base].  If you plan on capsize recovery you probably won't.

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