Yet Another Solo Mast Raising Question

[Joe11688]

Joe,

How do you have your mast crutch attached to the transom?

Years ago I took my boat to a metal fabricator and showed him what I had for a mast crutch at the time. What he did was cut my stern rail and welded two offset Ts. Then he took a 1" stainless steel pipe and cut it in half and welded a regular T fitting in the center and bent both sides of the pipe to resemble a hoop. He set up the hoop so that it fits into the two offset T fitting which slants in toward the cockpit.
He welded a flat flange to a straight 1" pipe and he installed a flange on the cockpit sole near the transom for this pipe to fit into. I made the wood crutch and attached it to the flat flange myself.
Years later I installed a roller in the wood crutch so that I could roll the mast forward or aft.
I had the hoop attached with fast pins and I used to remove the hoop and stow it in the cabin. After a while, I got real used to having that hoop on there and I decided to use bolts to fasten it.

When I first bought my boat, I made up a mast crutch out of plywood, pieces of 2x4s, two aluminum bars, and two bushing connectors from a high voltage substation transformer. The thing was heavy and fugly but it worked OK for a number of years but I wanted something lighter and easier with less work in breaking it down. The welder looked at it and came up with something of his own design right on the spot.
I stow the mast crutch in a compartment under the Port settee and I have a flag staff made of 1" pipe that fits in that T for my American flag.

 

[GorillaToast]

Darn.

I was hoping it would be something much simpler and les expensive. I've got a telescoping tubular PA speaker stand I'm trying to adapt. The crutch part was easy, but I just can't figure out a clean way to attach it to the railings.

I've got a great welder (person) who's done some stuff for me in the past. I guess I'll have to go see him again. $$$:cussing:

 

[Joe11688]

Darn.

I was hoping it would be something much simpler and les expensive. I've got a telescoping tubular PA speaker stand I'm trying to adapt. The crutch part was easy, but I just can't figure out a clean way to attach it to the railings.

I've got a great welder (person) who's done some stuff for me in the past. I guess I'll have to go see him again. $$$:cussing:

If you have a stern rail, you can build a mast crutch out of wood and attach it to the rail. You could make it so that it's adjustable. You could build it out of wood and 1" stainless steel pipe.
Here's a picture of Wayne's mast crutch. He's the guy that gave me the Gin Pole idea.

 

[ArtVandelay]

I'm guessing the only technical must have for the crutch is it has to be high enough so that the pulling action actually stands up the mast and doesn't just pull onto the mast step? I've seen some of the pics where its quite high, I'm going to set mine about 5' above the settee just to be sure.

 

[kenn]

I was hoping it would be something much simpler and les expensive. I've got a telescoping tubular PA speaker stand I'm trying to adapt. The crutch part was easy, but I just can't figure out a clean way to attach it to the railings.

We don't have a stern railing (aka pushpit). The PO welded pintles and gudgeons to a piece of steel 'T' -section fence post and this hands off of the rudder mounts (more pintles and gudgeons) during transit. This has actually lasted a long time.

In order to be able to support the horizontal mast when the boat's under way, I'm planning to fabricate a slightly more elegant crutch out of aluminum and put some sort of hardware that's similar to pintles and gudgeons on the transom, slightly off-center, so that the crutch won't interfere with the rudder. This might work for you.

I've also thought about drilling a hole in the transom lip and mounting some sort of 'socket' inside there to receive a mast crutch. Seems like more work than necessary, though, vs just bolting 2 more small brackets to the transom...

 

[s sauer]

I had a 1979 Hunter 25 that had a 'U' shaped mast tabernacle on the coach roof with one thru bolt holding the mast in slots in the tabernacle. With the boat head-in in the slip and one helper I was able to walk the top of the mast forward over the bow pulpit and put the cross bolt into the mast tabernacle. Then with the headstay and forward lowers attached to the mast; I attached the topping lift, holding the boom upright and perpendicular to the mast; I then used the four part mainsheet and boom as a tackle and lever arm to raise the mast as the mainsheet was tightened bringing the mast to vertical and the boom to horizontal. at that point the backstay and rear lowers were fastened at the chain plates and the standing rigging could then be tightend. Everyone else seems to be describing mast raising from the aft end of the boat,but this worked fine for me without any extra equipment.The helper was needed to start the mast upright and keep it from wavering off to the sides before the forward lowers came into tension.

 

[Joe11688]

I'm guessing the only technical must have for the crutch is it has to be high enough so that the pulling action actually stands up the mast and doesn't just pull onto the mast step? I've seen some of the pics where its quite high, I'm going to set mine about 5' above the settee just to be sure.

No. The idea behind the mast crutch is to support the mast however high it needs to be in order to clear the sliding companionway hatch when the mast is pinned to the tabernacle and ready to go up.
The Gin Pole will allow the proper angle needed to raise the mast from a horizontal position.

Years ago I added a 1" thick Teak board under my mast tabernacle on the cabin top. I didn't realize the advantage it provided back then until I started using the Gin Pole. Prior to that, I had to raise my mast crutch to a height within reaching distance while stradling the cockpit seats so I could lift the mast up by hand while standing on the sliding hatch.

Just that 1" height under the tabernacle allows mast raising without raising the mast crutch and the mast sits in the crutch almost horizontal.
I replaced that Teak block with a piece of 1" thick Trex last year.
Here's a pic of the Trex under the tabernacle, and the mast extrusion I made last month. The mast went up as easy as ever last month.

 

[billh]

Hey Art, I just posted some info on stepping my mast on my O'Day 26. Do not know the weight but it wasn't bad at all. Normally I raise it with my brother he-man style not a biggie at all. I leave all stays on save head stay and lift away. Brother holds and I put the second pin in then attach head stay and viola. But my post shows a new mast raising system I just made and used this past weekend.

Happy sailing

http://forums.oday.sailboatowners.com/showthread.php?t=139915

 

[billh]

This will work for your O'Day 25 as well. http://youtu.be/UfYTiKryKBc

 

[Joe11688]

This will work for your O'Day 25 as well. http://youtu.be/UfYTiKryKBc

I just checked out his youtube and left him comment on it. I like his Gin Pole set up. His boom crutch idea is a new and different wrinkle that I had never thought of.
I never realized that the mast on an O'Day 23 is top heavy while sitting on the stern rail ready to be pinned at the tabernacle.

 

[tkanzler]

Okay, so what kind of pressure does the gin-pole, or A-frame have to absorb? I wouldn't think very much, I was out buying the materials today and couldn't find any steel rods to hook up so I was thinking about some tubular fencing metal. It's not the strongest stuff in the world but I'm not sure how much of the energy is transferred through these to the chain plates, or does it go from the pulleys right to the mast leaving the a-frame/gin-pole pretty much load-free?

The gin pole can be under substantial compressive load. A thumbnail analysis of my own, 6 ft long supporting 150 lb of mast and sail, experiences around 400 lb (static) compressive load, more if the mast is bouncing due to jerky line handling when lowering, of course. Buckling is the most serious thing you have to guard against, as failure is sudden and catastrophic.

I used a galvanized fence post on my gin pole. The load is virtually all compression if you balance the fore and aft tension at the same place on the pole.
I think.....

Essentially, yes. More precisely, if the load vector on each side (mast side and deck side) both intersect the neutral axis of the pole at one point, which is the centerline in the case of a round tube. An eye bolt with eye nut, or pair of eye straps sharing mounting hardware, is close enough for such a small pole.

 

[Joe11688]

The gin pole can be under substantial compressive load. A thumbnail analysis of my own, 6 ft long supporting 150 lb of mast and sail, experiences around 400 lb (static) compressive load, more if the mast is bouncing due to jerky line handling when lowering, of course. Buckling is the most serious thing you have to guard against, as failure is sudden and catastrophic.


Essentially, yes. More precisely, if the load vector on each side (mast side and deck side) both intersect the neutral axis of the pole at one point, which is the centerline in the case of a round tube. An eye bolt with eye nut, or pair of eye straps sharing mounting hardware, is close enough for such a small pole.

This is so very true. I remember reading about this somewhere. There is enormous pressure on the Gin Pole. I made my first Gin Pole out of white Oak for this reason. I think my mast weighs about 60 Lbs.

 

[tschager]

On my Solina 27, I have integrated mast raising system. It consists of an a-frame attached to the deck. At the end, there is a multi-block system. Lowering/raising the mast is very easy. Baby stays are mounted at the centre of mast rotation and stay under tension at all times. IMO, this is very well thought out and safe system. I have used it number on times on the water when crossing low bridges. Setup time is about 5 minutes.

Mast down:

Mast up:

This mast raising system on the Solina 27 is really slick and the use of the roller furler is very intelligent. I've got a Hunter 23.5 with a Harken roller furler and have been using the main sheet to lift the mast. This means the extra distance for the angle the gin pole uses exceeds the actual length of the gin pole and the intended use (the jib sheet). The gin pole should be about 6 - 8 inches longer.

If I were to use the Harken Roller furler, there is no easy way to attach the furler mount to the plate on the bow pulpit. Any suggestions from Hunter owners out there with Harkens on how to stabilize the mast forward and upright to get the mount completed? Also, do any of the other owners with roller furlers have an issue with the compression load with the furler causing an issue with over-stressing the gin pole's capacity?

The point made about balancing the forward and aft pressure to ensure the gin pole is completely upright an unbent is spot on, but there is still the lateral force caused by all of the extra weight causing the issue if a single upright point failing laterally and bending the pole. I experienced this failure over the weekend while stepping the mast upward and was fortunate enough that it failed before any serious damage resulted (and was lucky enough that the mast landed in the cradle).

Any suggestions or help would be most appreciated - especially if someone makes an a-frame system like this Solina system that would attach to the bow rail or other hardware on my H23.5!

Thanks.

 

[watercolors II]

It's all about leverage

The height of the ginpole or A-frame determines the amount of leverage it applies to the mast, just like a lever is used as a pry bar to move or lift an object.

"Give me a place to stand, and I shall move the Earth with a lever" is a remark of Archimedes who formally stated the correct mathematical principle of levers.

Think of it this way, if the ginpole or A-frame is the exact same weight and length as the mast and is attached to the mast step (fulcrum) as the mast is then the weight of a nickel is all that is needed on the lever ginpole or A-frame to lift the other end.

The weight of a nickel would be correct if the lever was horizontal just like the mast but, the lever is vertical so the weight of the lever is canceled because it’s weight is now applied to the mast step, fulcrum. I think of it this way, my mast weighs 75 lbs. with one end lying on the ground carrying one half it’s weight only 37 1/2 lbs. is needed to lift the other end vertical and the higher I lift that end the lighter it gets because more of the weight of the mast is now transferred to the lower end lying on the ground.

So, I think that only 37 1/2 lbs of pull is all I need to lift my mast if my ginpole is the same length as the mast. I’m not a mechanical engineer, is the pull only 75 lbs if the the pole is 12 feet high, and 150 lbs. at 6 feet?

I’m thinking that the higher the mast crutch is, the more the weight of the mast is transferred to the mast step and the higher the ginpole A-frame the more leverage is applied to the top of the mast.

 

[LloydB]

Reconsider example. Twins on a teeter-totter, give one a nickel what happens? To the forces I mean. It's a given the other will also demand a nickel.
just my 5c

 

[Bosman]

Another mast lowering/raising system, again never seen in North America, is called in slang "tamed mother-in-law". Don't ask me why. In essence, it is a system that compromises dimensionally engineered tension spring that is installed inside the mast. As the mast comes down, the spring compresses and causes "counter weight" to the mast's mass. Apparently it allows user to raise the mast up single handed, as possessing "super human" strength. Below is the photo.

Free translation from Polish:
This patent, presented by "Hobby" company from the city of Czeladz, apart from its name makes a lot of sense. You will not be able to tame your mother-in-law, but lowering the spar will turn out to be much easier. The design works well with mast attachement system that is hinged. Installed inside the spar spring compresseses by the metal rod attached to the mast's base as a function of lowering the mast. The lower the mast is, the more compression force is generated, causing little force required to lower or raise the spar. The engineeres claim that even the breakege of the front stay will not cause dramatic fall of the mast. The only major requirement is to reinforce the deck around the mast, as it will be exposed to much higher forces acting on it.

 

[GorillaToast]

This is the coolest system I've seen.

Go the YouTube and search for "mast raising so easy".

I finally tracked down the company in Austrailia, but it was too expensive for me.

 

[Kordie]

When I owned a trailer sailer I bought a price of kit here in Australia to help raise the mast.

In essence it was a very heavy duty set of rubber straps encased in a nylon sheath.

You attached it to your halyard then to your trailer winch. Cranked the trailer winch until the rubber was stretched out and the mast just slightly moved upwards.

Then just a matter of one hand lifting the mast into position.

Lowering was the opposite.

Whilst my description might be poor the product worked very well.

http://www.youtube.com/watch?v=IkZ__nMEUpc&feature=youtube_gdata_player

This looks like it or similar.

 

[GorillaToast]

Yeah, that's the same company. What you don't see in the video is the stainless steel t-bar that rests in fittings permanently attached to your cabin bulkheads. That provides the same function as an A frame or baby stays. Besides the expense of a commercial product, I just saw myself hitting my shins on those brackets.

 

[Kordie]

I didn't have any fittings like that on my boat. Just the rubber strap.

That was about 5 years ago now, maybe it has evolved since I bought mine.