Mast Raising Alterations 26M

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Jimmyt
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Re: Mast Raising Alterations 26M

Post by Jimmyt » Fri Feb 14, 2020 6:17 am

Highlander wrote:
Thu Feb 13, 2020 9:58 pm
[quote=Jimmyt post_id=340371 time=<a href="tel:1581560912">1581560912</a> user_id=16979]
One more point BOAT... The gin pole stays were Highlander's idea. I just thought it was so good I copied him. But if you think it's a loser, you could share the grief with him too! :D

Sorry Highlander. Getting lonely here under the bus... :wink:
Bus what bus ! sounds more like a bulldozer ! :D :D :D

J 8)[/quote]

If BOAT wasn't growling at me, I'd feel left out :) . It's all good fun. I always welcome a challenge. Often times, a question or challenge gives me a much-needed new perspective.

I've got some heavier stainless, so I guess I could make new bottom brackets. I'm hoping that stabilizing the gin pole will allow the stock brackets to serve the purpose. I'll continue to overthink this for a bit before doing anything.

One additional concern. We are calculating a static load, and that may be lower than what actually occurs. I notice that between an inconsistent winch grind, mast flex, and lifting rope flex, there might be some dynamic loads worth considering also. The system seems to bounce a bit on the way up and down.

Make that two. Actually, if you look at where the winch handle is, and forces on the handle during raising, a pretty fair moment is acting on the bottom bracket during grinding... unless you are steadying the gin pole with your other hand. I'm usually fighting the furler with the other hand. Glad my gin pole has stays to resist that moment BOAT :wink: :D

Tomfoolery' rig that controls the furler with the gin pole is a really nice solution to that issue.

Maybe the galley table will be next. Should be less controversial 8) .

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Re: Mast Raising Alterations 26M

Post by Tomfoolery » Fri Feb 14, 2020 6:33 am

Jimmyt wrote:
Fri Feb 14, 2020 6:17 am
I've got some heavier stainless, so I guess I could make new bottom brackets. I'm hoping that stabilizing the gin pole will allow the stock brackets to serve the purpose. I'll continue to overthink this for a bit before doing anything.
Consider adding a filler block of lightweight plastic or wood that fits snugly inside the brackets to stabilize them. A few small holes in the center, along their length, to secure the block and transfer longitudinal shear (up/down in this case) will make those brackets much much stronger. Especially for the :macm: , where the MRS doesn't move, you only need little lugs at the bottom to engage the tabernacle.
Jimmyt wrote:
Fri Feb 14, 2020 6:17 am
One additional concern. We are calculating a static load, and that may be lower than what actually occurs. I notice that between an inconsistent winch grind, mast flex, and lifting rope flex, there might be some dynamic loads worth considering also. The system seems to bounce a bit on the way up and down.
Oh, yeah. Dynamic loads are significant with those systems, as that big, long mast and stretchy rigging can result in a lot of bounce. Peak loads could easily be twice the static load.
Jimmyt wrote:
Fri Feb 14, 2020 6:17 am
Make that two. Actually, if you look at where the winch handle is, and forces on the handle during raising, a pretty fair moment is acting on the bottom bracket during grinding... unless you are steadying the gin pole with your other hand. I'm usually fighting the furler with the other hand. Glad my gin pole has stays to resist that moment BOAT :wink: :D
Winch grinding puts side load on the pole, but the pole has plenty of buckling resistance. Not so much the brackets, though. See above for a filler piece to stabilize them. Or just make heavier ones.
Jimmyt wrote:
Fri Feb 14, 2020 6:17 am
Tomfoolery' rig that controls the furler with the gin pole is a really nice solution to that issue.
But my gin pole moves with the mast, so the forestay orientation to the mast and gin pole is constant as the mast goes up. But I've seen other similar techniques used with the M style system, but I don't remember the details.

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Re: Mast Raising Alterations 26M

Post by Jimmyt » Fri Feb 14, 2020 6:45 am

Will consider reinforcing brackets.

I'm thinking that the winch handle is side loading the gin pole (in addition to twisting,etc), which is causing a moment at the brackets. Maybe it's not significant.

Yes, I realize that your gin pole moves with the mast, making a furler solution easier to implement than with the fixed gin pole I have. I just think it's a nice system that you have. Unfortunately, I'll have to think to solve how to control my furler. Not what I do best :P .

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Re: Mast Raising Alterations 26M

Post by Tomfoolery » Fri Feb 14, 2020 7:07 am

Jimmyt wrote:
Fri Feb 14, 2020 6:45 am
Yes, I realize that your gin pole moves with the mast, making a furler solution easier to implement than with the fixed gin pole I have. I just think it's a nice system that you have. Unfortunately, I'll have to think to solve how to control my furler. Not what I do best :P .
But others here have done something ingenious with their :macm: system gin pole to control the forestay/furler/head sail. I just don't remember the details. Hopefully others who know what it was will chime in. Maybe search some old threads, though photobucket and tinypic have made a LOT of good stuff go away forever. :x

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Re: Mast Raising Alterations 26M

Post by BOAT » Fri Feb 14, 2020 8:38 am

I have not had time to make a picture yet - the gin pole in the MRS system is a sort of "gadget" - it is a device the factory came up with that is supposed to do it all with one device. Even the baby stays are attached to the gin pole "technically" because when you remove the gin pole the baby stays go with it.

That was the factory design because it was supposed to be a "thing" they could sell you that was all one piece.

A guy in a slip who steps the mast once every 6 years is not going to care about such a device. But a person who is stepping the mast over 30 time a year (like I am) is going to want something "all in one" that does not muck up the rig. So you have this pole with a winch and pulleys and cables and rope and all the "muck" stays on that "thing" and goes away when your done stepping the mast.

I'm pretty sure the original x boat system had the baby stays attached to the mast. If it's good enough for the X maybe it would work on the M? (BIG maybe because the M mast rotates - another reason the baby stays are on the BALE and not on the MAST).

Baby stays on the gin pole is a statement about the inherent instability of a gin pole and thus why boat builders have put stays on gin poles for hundreds of years but then is it a gin pole anymore? - or is it a "Sprit" - that is the proper sailing term.

The original word GYN is old english and more akin to what highlanders ancestors used to lift the big rocks at Stonehenge whereas the British people that came later just said GIN and it was a word that meant 'BEGIN" (be-GIN - so to GIN UP something was to start something). When primitive British Druids heard Highlanders ancestors "be-GYN" the lifting process they just slanged up the word to GIN because that's what they thought he was saying. Thus a GIN pole was to start a lift - used on derricks and so forth even before boats were around.

The Sprit on the boat has stays and stability to hold up the mast. Thus, a pole with stays used to hold up a mast is a 'Sprit' - not a Gin Pole.

All that is to say that I think we should eliminate the gin pole altogether and the winch too - both of them landlubber tools that don't belong on a boat anyways. A single heavy whisker pole mounted to one side of the mast could be used to stabilise the mast during the lifting process and allow the use of the spinnaker bale to lift the mast with a block instead of a cranky winch thus reducing the pressure on the system immensely and making the whole process much easier to do, safer, and make the equipment more portable. A 'windlass' belongs on a deck - not bolted to some silly pole.

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Re: Mast Raising Alterations 26M

Post by Jimmyt » Fri Feb 14, 2020 10:51 am

Maybe I should forget about gin poles and concentrate on gin and tonics.

Great post BOAT! Educational, witty, sarcastic, and makes several astute observations.

Baby stays definitely can't stay attached to the mast on my M. Once I got them tight enough to limit mast sway, mast rotation will be inhibited. I put snap shackles on them at the stanchion end, and will clip them into my gin pole stay loops so they're slack enough to allow rotation. Having them stay on the boat is a small price to pay for the greatly reduced mast motion (I hope). Like you, I trailer every time. It will mean that there are a couple of new things in the way of getting to the foredeck.

The gin pole stays are permanently mounted to the gin pole. Snap shackles secure them to the new stanchion loops, letting me unsnap them and remove them with the gin pole as before.

I actually like the "sprit" and brake "windlass" (a rose by any other name..). Like everything else I have, if it still works, I obviously haven't implemented enough enhancements. 8)

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Re: Mast Raising Alterations 26M

Post by Tomfoolery » Fri Feb 14, 2020 12:56 pm

BOAT wrote:
Fri Feb 14, 2020 8:38 am
I'm pretty sure the original x boat system had the baby stays attached to the mast. If it's good enough for the X maybe it would work on the M? (BIG maybe because the M mast rotates - another reason the baby stays are on the BALE and not on the MAST).
Yes, baby stays attach to the mast. I usually unhook them at the deck and just bungie them to the mast to keep them out of the way if I'll be needing them soon.

Don't know if you can see the baby stays in the photo, but they're there.

Oh, and the gin pole is inherently unstable IF the hinge point is higher than a straight line between the lower block attachment point on the deck and the halyard or MRS line attachment point on the mast. If the hinge line is lower, the gin pole could just stand there with only a single knife edge contact with the tabernacle. Both systems are close, so a flared attachment scheme makes sense. Baby stays to the gin pole are obviously far more stable still.

Image

Image

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Re: Mast Raising Alterations 26M

Post by BOAT » Fri Feb 14, 2020 3:38 pm

YEAH, BUT!

Tom, what about ONE stay only on one side? A SOLID stay - a POLE - can the mast sway if there is a solid pole on one side? I don't see how it could - it can't move to the port because the pole would stop it and it can't move to the starboards either - one side is a push and the other side a pull - your basic right triangle.

The mast could only go up, or down.

That Pole could double as a whisker for the jib, or even as a stay for a storm jib. If you attached the main halyard to the end of it you could also use it as a crane for lifting the dingy out of the water.

It could also be used as a spinnaker pole.

And it's a lot easier to stow a block and tackle and some line than a silly trailer winch bolted to a pole.

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Re: Mast Raising Alterations 26M

Post by Tomfoolery » Fri Feb 14, 2020 4:00 pm

Yes, you absolutely could use a rigid pole on one side.

BUT, the bottom pivot point would have to be on the same line with the mast hinge line, or the mast will either not line up with the crutch, or not be vertical when all the way up (leaning to one side or the other). Not just aligned fore/aft, but also in elevation.

The baby stays, being tension members and flexible, can be tight with the mast in the crutch and get loose as the mast approaches vertical, since the side stays will straighten it up anyway. The pole has no such ability unless you build it in. Or locate the lower mount in exactly the right place, which is doable, but not necessarily very elegant.

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Re: Mast Raising Alterations 26M

Post by Jimmyt » Fri Feb 14, 2020 4:28 pm

Tomfoolery wrote:
Fri Feb 14, 2020 12:56 pm

Oh, and the gin pole is inherently unstable IF the hinge point is higher than a straight line between the lower block attachment point on the deck and the halyard or MRS line attachment point on the mast. If the hinge line is lower, the gin pole could just stand there with only a single knife edge contact with the tabernacle. Both systems are close, so a flared attachment scheme makes sense. Baby stays to the gin pole are obviously far more stable still.
Thanks for that! I'm sure I'm supposed to know that, but 30+ years of designing HVAC, plumbing, and fire suppression have left me lacking in machine design skills. :(

Just sighted it. The gin pole pivot appears to be a couple of inches (at most) lower than the bow cleat and mast connection point. I guess that's why the system works fine if I don't grab the gin pole.

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Re: Mast Raising Alterations 26M

Post by Jimmyt » Fri Feb 14, 2020 7:19 pm

Image

The scale model of my geometry shows that the system is stable as long as the mast stays centered (the model gin pole has a point on the end that rests in a conical depression in the deck). Tomfoolery is da man! As the mast swings away from center, the gin pole leans with it, but keeps the mast supported. If there was a ball joint at the bottom of the gin pole, it would just lean over and scare the crap out of you. That is, until the mast gets several feet (at the far end) off centerline. At that point, the gin pole hits the deck, and the excrement hits the fan.

The higher the mast gets, the more stable it all becomes, however bracket deformity is still likely if the mast is allowed to significantly move off of centerline. The brackets are the problem. Who's going to try a ball joint? 8)

If you keep the mast centered, you can flick the gin pole and it will pop back to center - per Tomfoolery's statement.

Tomfoolery probably knew this already. I had to model it, to see the system react to various degrees of mast sway, so I could get a feel for it.

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Re: Mast Raising Alterations 26M

Post by Tomfoolery » Fri Feb 14, 2020 7:42 pm

Yikes! I didn’t know this was going to be on the test. I’d have been a little more thorough. :|

If you want to prove the unstable part, put the mast butt and gin pole butt on a raised block so the foredeck attachment is lower, relatively speaking. The gin pole won’t stand up on its own, since the mast will tilt down as it flops to one side or the other.

The problem with the lugs on the bottom of the gin pole is that being relatively rigid, it only takes a very tiny movement off-plumb to put all the load on just one of them. And they seem to be the weak point in the system.

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Re: Mast Raising Alterations 26M

Post by Jimmyt » Fri Feb 14, 2020 7:50 pm

Some people work crossword puzzles... I just have a need to understand what I'm dealing with. Your stability comment made me second guess my gin pole stay project, so I wanted to get a better understanding of the system.

You passed the test with flying colors :D . I appreciate your exchange! I will admit that I was a little amused when I flicked the gin pole off center and it snapped right back! :)

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Re: Mast Raising Alterations 26M

Post by Jimmyt » Fri Feb 14, 2020 8:13 pm

Everyone's looking for a better mouse trap (mast trap?).

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Re: Mast Raising Alterations 26M

Post by Tomfoolery » Sat Feb 15, 2020 6:08 am

I don’t remember the manufacturer, but there’s a boat out there somewhere with an integral V-shaped ‘gin pole’ arrangement that fits neatly at the bow rail when not used. Couldn’t find the video or photos, but they’re out there somewhere. Neatest factory arrangement I’ve ever seen. :wink:

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