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PostPosted: Thu Sep 14, 2006 10:56 am 
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Site Rank - Deck Hand

Joined: Sat Apr 17, 2004 4:34 pm
Posts: 20
Location: Middletown, CT
I have been working on a mast clamp that clamps aroung the mast about seven feet from the base. The clamp is about 2 feet long with a mast cut out in the center. It is hingeg on one end with a hasp to secure it closed. the clamp has an eye hook on each end with a bridle that is permanently fixed on the forward side of the mast and secured with a shackle on the stern side. The mast raising line attatches to a ring on the midlde of the bridle forcing the mast to be raised on its side. Once raised, uclipping the stern side of the bridle allows the mast to rotate into its normal fore aft position and can then be secured. The clamp is then removed by unclipping the hasp and opening the clamp. The mast can be lowered in the oposite manner. My thought is to mount a padeye to the top of the trailer mast stand and use the winch on the trailer to raise and lower. My concerns:

This system will not stop sideways sway as you raise the mast

When hoisting by hand the lifting of the mast will remove much of the strain on the ball at the base of the mast, using my clamp, the first several degrees of lift will direct much of the force to the ball, too much? I don't think so but don't know.

I made my clamp using oak and readily avaliable hardware and if you are interested will hapilly share photos and drawings. I would post here but am not that computer savy.

Craig Nielsen


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PostPosted: Fri Sep 15, 2006 9:29 pm 
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Joined: Sat May 21, 2005 11:32 am
Posts: 183
Location: Portland, OR
You're absolutely correct that if the mast foot was hinged, as the H16 is, there would be no problem.

When I first looked at getting a mast stepping system, I found some reference from the makers of these systems that specifically said they were not to be used on boats where the mast is sideways during the raising operation. Unfortunately, I can no longer find this material, and I'm loath to buy a system I would then have to return because it doesn't fit.

I wish the manual for these systems were posted on the Web so that we could determine their suitability before purchase :x End of rant.

The Getaway is a recreational boat, so presumably targeted at people who may not be in as great a shape as your typical H16 sailor. I'm 6'2 and 200lbs, and can lift the Getaway mast without mechanical help, but my wife certainly can't. If I get hurt, she's stuck. Why Hobie has not seen to address this issue blows me away because they've traditionally be very responsive.

Anyhow, it looks like the weather will cooperate tomorrow so I'll try the loop around the mast idea from Bill a few days ago, and see if I can make it work to raise the mast from the horizontal without having to manually lift it! I'd rather be on the water than in my drideway solving mechanical problems, but I've got to find a solution...


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PostPosted: Sat Sep 16, 2006 4:37 pm 
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Joined: Sat May 21, 2005 11:32 am
Posts: 183
Location: Portland, OR
Some good news :) and some not so good :( ...

First thing I did this morning was to take some measurements so that I had an idea of the forces involved. Here there are:
Mast weight: 50 lbs
Distance from rotation ball to mast center of gravity: 14'
Distance from rotation ball to point of lift (jib tang): 17'
From this I deduced that I needed to lift about 40 lbs
Angle between mast and lift strap: a little over 6 degrees
From this I caculated that the force on the strap would be around 400 lbs: 40lbs * SIN(6degree)
This should not present any over large stress on the ball, the lift strap, etc.

Next, I started rigging a loop around the mast, connected to the main halyard (so that I can lock it at the level of the jib tang, and lower it once the mast is raised), with two temporary stays connected to eye strap on the wing supports to prevent sideways motion. I connected the winch strap to the loop and started cranking. Even though the numbers from my calculations looked good, the stress on the loop scared me somewhat and the shackle connecting the halyard scratched the mast. :? So I decided to go back to the original idea (using the forestay to lift).

Plan B: I connected the temporary stays directly to the Jib tang (I figured I would leave them connected while sailing and simply tie the lower ends against the mast). I connected the winch strap to the forestay with a shackle. Time to start cranking. The lifting strap gets very taught, but things look good. I'm much more confident in this system that my previous loop around the mast. The temporary stays are very effective at keeping the mast reasonably in line all the way up. The mast stays sideways almost 2/3 of the way up, then slowly rotates fore-aft. Success, the mast is raised :P .

Now, le's reverse the maneuver. As I start lowering the mast, it stays in its fore-aft position and the rear part of the mast foot aluminum casting binds against the SS bolt that holds the ball. To ensure the mast remains sideways, I then connect the main halyard to the winch strap (along side the forestay) so that the strap pulls on both the front (forestay) and back (main halyard) of the mast. Why didn't I think of that sooner? :)

2nd attempt at lowering the mast. The halyard is not tight enough and the mast sill rotates as it goes down. The heel of the mast step casting forces it back sideways, but I don't like the stress so I crank everything back up to tighten the halyard.

3rd attempt. This time the mast stays sideways as it goes down. However, there's a couple of jerks and then, as the mast is almost down, the front part of the mast step casting flies off! :shock: I lower the mast the remaining foot or so to the ladder I use to prop it, and survey the damage. Sure enough the entire forward part of the mast step casting is gone (see picture).

Image

The couple of dents in the middle of the rounded part of the casting are due to my first attempt at lowering the mast when it bumped against the SS bolt. The third one more to the side is from my 2nd attempt.

I can't determine what forced the casting to break. The mast stayed sideways the whole time I was lowering it, and I can't see any marks of stress on the crossbar. I'm puzzled :? Did the SS pin get caught? It doesn't seem long enough the reach the big nut that attaches the ball bolt to the crossbar.

It doesn't look like this should prevent the mast to function once up, but I still need to replace the casting (I don't know how much of a problem I have with the broken casting). Matt, if you read this, can I order the mast base (37641001 I believe) and rivet it?


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PostPosted: Sat Sep 16, 2006 6:08 pm 
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Joined: Sat May 21, 2005 11:32 am
Posts: 183
Location: Portland, OR
When I first read Craig's post, I thought he was describing a custom gin pole, but on closer read this is a small fore-aft temporary "spreader" with a bridle to force the mast sideways.

The idea as described would keep the mast sideways, but with the lifting cable or strap connected only 7' up the mast instead of the 17' of the forestay tang, the force needed to lift from there will be 100lbs, and with the acute angle from this point to the top of the trailer mast stand (I estimate about 10 degrees), this results in a force of about 575 lbs on the winch to start lifting the mast, and about the same on the ball.

Unfortunately, if you don't pull from the clamp bridle, nothing keeps the mast sideways, so I'm not sure this will work.

Let us know if you have better luck than I!


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 Post subject: Almost broke mine.
PostPosted: Sun Sep 17, 2006 8:10 am 
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Joined: Sat Aug 19, 2006 7:26 am
Posts: 18
I almost broke my casting once by coming down sideways on the wrong side. I'm not sure where my head was at that moment. Just went brain dead for a bit. By the time I realized that I was coming down on the wrong side I bent the mast foot bolt. I got lucky. Casting looks fine and it still rotates fine with a bent bolt. One other note: I was at a county fair last week and found this great product for welding aluminum, copper, brass and galvinized steel. All you need is a any torch and it bonds stronger than the original material. If you still have the other part of that mast foot casting,...then I think you could fix it, or better yet, use it as a part for making an experimental hinged foot.


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 Post subject:
PostPosted: Sun Sep 17, 2006 10:36 am 
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Joined: Sat May 21, 2005 11:32 am
Posts: 183
Location: Portland, OR
I never understood why the mast should only come down on the side marked with the arrow. The casting looks perfectly symetrical, and so is the ball (obviously).

I always make sure to bring it down on the correct side (simply because it says so in the instructions), but I've often wondered if it would make any difference.


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