Mast raising mod question

[Ormonddude]

I certainly dont want anyone hurt my only point was if your competent and maybe need to save $50.00 a standard winch works fine. However if your gonna have kids or wives helping you I agree with you completely.

[Sea Wind]

Put a single block with at least a 700 lb SWL on the eye strap on the same side as the winch, and use the other eye strap,

couldn't you use one of the fiddle blocks from the old MRS and use it as a single block?

[Tomfoolery]

Put a single block with at least a 700 lb SWL on the eye strap on the same side as the winch, and use the other eye strap,

couldn't you use one of the fiddle blocks from the old MRS and use it as a single block?

The forces are probably a lot higher. I get something like 300 lb or so with a 150 lb (total) mast and headsail and so on using the old style system, and that's total static load, spread over two sheaves.

With the system, and the mast laying down, the line is nearly turning back on itself (like 135 degrees), so with a 350 lb linepull*, the load on the block is something approaching 700 lb (again, static), and that's on just one sheave of the two.

I'm not sure I'd trust those blocks of unknown manufacture and capacity, especially when the result of failure is sudden and catastrophic. Like that of a cast iron crane hook.

*The geometry is different, which is why the force is different.

[jazaddict]

I gotta admit, the force necessary to raise & lower is greater than the wifey or kid could control. That said, its more than managable ....its really just fine for me.

I guess I'll look for a brake winch ....BUT ONLY CUZ YOU GUYS SAY SO

[island808]

I bought a winch to do this modification, but before i bought the bolts to mount it, i found that it was already super easy to raise the mast, and easier to stow if i just used a 4:1 and a wrap around the winch. I don't even use a winch handle, just use the winch so i can adjust my grip safely. Easier to pull up than the centerboard. Even had my nine year old crank it just to let him in on the fun.
My MRS stays are super tight though. Can barely bolt the mast when theyre on. Makes the whole process feel a lot safer than even just a little more slack.

[Catigale]

Well, a standard winch is safer than raising by hand, which is what I do now.

But, I'm headed to Harbor Freight for that brake winch next time it's on sale....

[island808]

I guess slightly. I mean. I can run it through the cam cleat for added safety.

Only way its getting away from me is if i slip and fall badly.... Which is possible.

Looped around the winch drum ... You can hold it with your teeth..

[Sea Wind]

I got it from northern tools for $60
http://www.northerntool.com/shop/tools/ ... _200331203
my question for those of you that have done this mod is about the base of the winch. If you look at page 8 of the manual it shows the base and the holes for the screws in a T shape:
http://www.northerntool.com/images/down ... 129681.pdf
how did you install it? I was thinking in drilling a new whole so there would be two in a row parallel to the mast raising tube.

[Tomfoolery]

I was thinking in drilling a new whole so there would be two in a row parallel to the mast raising tube.

I don't know what BWY does to the 350 lb DL winches they supply on the MRS, but it has two bolts through the pole. Presumably, one is in the original hole, and the other I would assume they drilled the winch for.

The hollow tube is going to be the weak link here, assuming decent quality hardware.

[Sea Wind]

The hollow tube is going to be the weak ... hardware.
yes, I thought about that. Thanks!

[Kittiwake]

I was thinking in drilling a new whole so there would be two in a row parallel to the mast raising tube.

I don't know what BWY does to the 350 lb DL winches they supply on the MRS, but it has two bolts through the pole. Presumably, one is in the original hole, and the other I would assume they drilled the winch for.

The hollow tube is going to be the weak link here, assuming decent quality hardware.

I am no engineer or mechanic so I certainly defer to you guys; but I would just add that, as I mentioned in an earlier thread, on my 26M it was the stock "mast raising system pole straps" that bent (ie. not the hollow tube) when the mast collapsed slowly to the '11-o'clock' position as I was lowering it. These "pole straps" are the two metal 'ears' that form the fork through which the bolt passes to hold the MRS to the mast step. As also mentioned in that thread (by others), it may be important to have the MRS stays nice and tight (I did not: I had simply left them as they came when I received the boat several years earlier). Island808 notes above in the present thread that he keeps his MRS stays "super tight". I only bring this up because I was so impressed with the forces involved, and perhaps others out there (like me) do/did not concern themselves with the MRS-stay tension. As Tkanzler noted on the earlier thread, BWY does supply replacement "pole straps" if you have any concerns about yours: I have replaced mine from that fine source!
Kittiwake

[Tomfoolery]

As Tkanzler noted on the earlier thread, BWY does supply replacement "pole straps" if you have any concerns about yours: I have replaced mine from that fine source!
Kittiwake

Did you notice any difference between the new ones and the old ones that failed?

[Kittiwake]

As Tkanzler noted on the earlier thread, BWY does supply replacement "pole straps" if you have any concerns about yours: I have replaced mine from that fine source!
Kittiwake

Did you notice any difference between the new ones and the old ones that failed?

Good question! No, they look to be identical.
I wonder if they can be subject to weakening by abuse over time (at the points where they are bent during manufacture to give them their final shape): eg. I'm sure many of us have kinked a stay or hooked a spreader under a lifeline while trying to raise the mast, with resultant excessive strain on the mast-raising system before you realize why the mast isn't moving.
Kittiwake

[seahouse]

While I hope I'm not giving credit where credit is not due, I believe that the material, and design of those two tabs at the bottom of the MRS was done purposely and with careful consideration at the factory. (And I doubt they would deny that! )

I notice that when bringing tension with the MRS winch to hook in the forestay pin that if I go to the point where I think these two tabs are about to collapse (so that the forestay pin can be inserted) the tension on the shrouds (as measured with a Loos gauge) ends up being in the correct range after the forestay is pinned and the MRS relaxed.

While I can't be certain of this theory without testing to failure, it does make sense that the angles were chosen so that the tabs would collapse before further damage is done elsewhere in the system, and still offer some elasticity before that happens. It's the most obvious point that can be easily engineered to fail at any pressure chosen.

As you say, Kittiwake, the failure you experienced was under conditions (of direction and force) that it would not be put under in normal use.

[island808]

I make sure to keep my mrs stays super tight because the first time i touched the mrs, was to lower it at the boat broker's lot. the boat was on jacks on a port side slant. As soon as i got the mast down a few degrees, it swung way ought over the parking lot with the tension the PO had the stays at. Not comfortable or good for the mast i imagine. Never mind, i was in the throws of heat exhaustion and was well aware that my judgement may have been clouded. also, it was the first time i ever lowered any mast. I half expected it to slam down the second i unpinned the front. I actually tied it off to the trailer loop just in case.

Thought it a good idea to tighten up the stays as much as possible on the trailer so if i ever had to take the mast down at sea (almost happened once due to losing a halyard up the mast like an idiot 5 miles from shore). The thought of taking the mast down with loose stays is terrifying. Im a bit in disbelief of those videos ol' mac shows of just dipping under a bridge like its cake. Not too far off if you don't film pinning the forestay i guess. If you lay the mast down and tighten the stays up to where you need to wrestle the mast to pin it at the foot; the mast wont be able to swing but maybe a degree or two. No room to build massive inertia and start to break things. Since the mrs stays are in line with the mast, they maintain tension on the way up.

As to the pole strength... It shouldnt have much stress put on it. Its merely a fulcrum. I guess the winch adds a bit of stress.. I might think of tacking a sleeve on it if i were to add a winch. Then again, i left my tig in hawaii.