Gin pole force calculations?

[warren631]

I need to calculate the loads on the gin pole and associated lines. Any good links to calculating mechanical static forces at different angles?

I am thinking of designing a system that is permanently installed and quick and easy for a single handler. Mount the heavy clutch winch permanently on the prow (can also use it to pull up the anchor?) (also use it to pull onto the trailer?) (12v electric winch with remote control?). Associated gin pole lines easily permanently installed. Use light weight PVC pipe for the actual pole (is it strong enough? - calculate it). Permanently attach the pole to the mast. Any more ideas?

[Catigale]

PVC will be strong enough because it's in compression , where plastic is good, but it will weaken with age and UV and shatter one day. That makes it unsuitable for that application.

Tom will crank out his CAD soon, I'm sure. I'll try to play with this on the plane too

[Tomfoolery]

It's not a simple problem as you have to consider not only static forces, but material strength, Euler buckling in the pole (including any bending moment induced by accentric loads), connection details, etc. The statics part is easy (external tension, pole compression, and reaction forces), and if you search the forum, I have some cad sketches posted with geometry and force estimates, which you may find helpful.

Can't do much analysis on a cel phone, though (not at work right now)

[warren631]

A Google search on "PVC Lifetime" says "The expected lifespan of PVC pipe is 50 to 70 years" but suggests buy “UVR” type or paint it white to protect against UV. Maybe the boat should be made out of PVC.

[warren631]

I couldn't find your calculations Tom. Thanks for any help.

[sailboatmike]

A cheap Aluminium painters extension pole or Pool cleaner pole will do the job.

I picked one up this week at the recycle shop for $2

[Hamin' X]

Try this post:

http://www.macgregorsailors.com/forum/v ... ad#p310245

~Rich

[Phil M]

A cheap Aluminium painters extension pole or Pool cleaner pole will do the job.

I picked one up this week at the recycle shop for $2

Are you referring to a whisker Pole? I made my whisker Pole from a pool cleaning extension bought at Walmart but I wish I would have bought the painter extension available at Home Depot instead.

[Highlander]

I would not be using a plastic pole for a gin pole for raising or lowing the mast there r more than just compression forces on the gin pole when the mast swings sideways which it will do when lowering or raising on a windy day or while doing so on the water , many on here have had the gin pole S/S base brkt,s bend when this has happened , including myself , so just imagine the side forces in play here @ the bottom of the gin pole , there,s a very good reason that there is s/s wire baby stay,s on the gin pole to start with , I even added an extra second set of baby stay,s to the top of my gin pole because I was bending the gin pole base brkt,s to many times for comfort
Just remember if that plastic gin pole breaks u or a crew member could be hurt if that mast comes crashing down on U , or even worse while standing beside it while cranking the winch & it should shatter u could get impaled by it not withstanding the damage that could be done to ur mast & or boat for the sake of the price of an thick wall Alum gin pole
U already have three potential fail points with the MRS poss. winch failure , the gin pole anchor line which goes to the bow cleats , the winch line that goes to the mast , why add one more !
that,s why it,s a good idea to use ur spinn halyard as a secondary back-up when raising & lowering the mast , i do although not always

Just my thought,s on this do not want to see someone get hurt or damage their boat !!

J

[sailboatmike]

A cheap Aluminium painters extension pole or Pool cleaner pole will do the job.

I picked one up this week at the recycle shop for $2

Are you referring to a whisker Pole? I made my whisker Pole from a pool cleaning extension bought at Walmart but I wish I would have bought the painter extension available at Home Depot instead.

Yeah thats the one, must of been having brain fade, my gin poles are 5mm wall aluminium tube of around 40mm diameter

[warren631]

OK. I agree - no PVC gin pole.

I still want to remove the winch from the gin pole and permanently mount it on the bow railing (so its up and out of the way of the jib furler drum and anchor chain) - will the railing be strong enough (the railing is screwed to the deck at four points)?
- And store the gin pole permanently hinged at the bottom of the mast and bungeed against the front of the mast when not in use for quick setup.
- Also the line between the gin pole and mast permanently attached at both ends (also bungeed against the mast when not in use).
- Also the gin pole side stays (also mast baby stays) permanently attached.
- Also attach/detach the jib furler with some kind of LARGE RELIABLE and EASY TO USE QUICK disconnect/pin mechanism (I hate those silly little cheap spring clips).

Then all I have to do is take off the bungees and attach the winch line to the top of the gin pole and start winching up or down.

I'm thinking of about 45-60 degrees between mast and gin pole when its in use so that the top end of the gin pole is still above the winch when the mast is fully raised.

Another question - why do I have to detach the mast and pull it forward for trailering? It will still be supported and bungeed to the aft mast support post. I know the mast will stick out behind the trailer about 8 ft. but can't I just add a red flag on the end and a "long load" sign on the transom? Maybe also increase the height of the aft mast support post so the top of the mast is up high when trailering (but clears under any bridges).

Comments/suggestions appreciated!

[sailboatmike]

Not sure any of this would be an actual time saving.

Gin pole takes at best 2 minutes to set up, Im sure it would take the same or more to unstrap it and set it up from what you have planned.

[warren631]

Mike, I would like to see a two minute video of you installing the gin pole. It takes me at least one minute just to get the pole and wrenches from where they are stored, figure out which way is up and which way around it goes, and bolt it to the bottom of the mast - but I guess I'm old.

[Cougar]

Okay, so it may take a couple of minutes longer. I would stow away the gin pole anyway, just to keep it from the elements. Don't underestimate the effect of prolonged UV on the winch rope. It may soon prove to be the weakest part of the mast raising system.

[Russ]

I believe Sumner keeps his pole attached like this.



http://purplesagetradingpost.com/sumner ... ing-2.html