Tabernacles - Mast Hinge

[hectoretc]

Wow... interesting... That is a serious looking step assembly.
Looking at the photo, it appears by the finish, to be on the cuddy floor... is it further reinforced underneath?
I guess the fact that the cuddy floor is a solid sheet (except in my case) of 1/8"? fiberglass afixed on all sides, there really isn't anywhere for the foot (step) to go as long as its firmly attached to the fiberglass and the subfloor step base holds up. And I assume futher that the mast step base under the floor is designed for the mast, sail and associated hardware "weight" which hasn't increased for all of our work, it's the lateral strength that is being tested by the new mast hinge dynamics. But is it really all that different?

The mast/boom relationship hasn't changed, the boom has always been there applying it's flex pressure on the mast. That's no different than the stock step up. I can see however that adding a coupling of any kind inside the cuddy could compromise the rigidity of the complete mast unit. That couplers gotta go and I need to at least replace that entire lower section with a solid one piece unit.

I really like your adjustable step, and I'll probably look at doing something similar if not copying it altogether, other than I can't imagine where to get that erector set looking piece. (maybe my old erector set...)
Barring that, I think the same thing could be accomplished (in a non adjustable version) by distributing the lateral pressure over a larger foot. If I were to take even an round (or square) steel 4 x 4 electric box cover and bolt the step to it, and then screw the plate down to again distribute the lateral pressure over a larger (and more screws) area it should work.
I think you're comment about the significant pressure on the partner (cuddy blowhole) coming from your A frame lifting from the horizontal is valid, but if I'm doing more of the standard "walk it up from the back" mast raising, I don't think I'm seeing why that would incur any more pressure than the low mounted tabernacle. I guess there's about 2 ft more of a lever above the cuddy that I'm pressing against... so maybe.
So that's forward pressure on the top of the lower mast section. I've got to go back in and look at the inside of the cuddy roof, but just thinking out loud, If Iwere to take a 1" piece of plywood, cut the blowhole out (tight) and then bolt that piece (as big and wide as it can be) through the cuddy roof, that would have to be enough strength to offset that extra pressure wouldn't it?
All this mental exercising is fun, but it makes my brain tired. I should have paid attention in my advanced mechanical analysis class... oh wait... I never took anything like that... Maybe that's the problem...

[GreenLake]

@hectoretc: I think jdoorly's designs are always well thought out and definitely up to any loads that you can throw at them, but having seen similar designs on other small boats, I think some of them just may be a tad stronger than is required...

However, he's correct that the strongest fore and aft loads come when the upper mast section is raised by pulling on the forestay (or via ginpole). At low angles, the leverage is poor and there's a lot of forward force. (Possibly more at some angles than your boom delivers while sailing).

With a deckstepped mast, or a compression post ending at the deck level, the mast partners (cuddy opening) will take that force directly. With the elevated mast hinge, the partners act as a fulcrum.

This will stress your joint. and may stress your mast step on the floor. The joint I would test. Can it hold your weight? If so, that may be enough. Otherwise, it's easy to sleeve, either with metal or fiberglass to make it more solid.

The partners on my DS1 are reinforced by additional fiberglass around the opening. However, a previous owner added a plywood backing plate and a metal disk (the latter above the deck). They effectively add further strength, even though their primary purpose was to attach some other hardware.

[jdoorly]

Wow... interesting... That is a serious looking step assembly.
Looking at the photo, it appears by the finish, to be on the cuddy floor... is it further reinforced underneath?
Yes, it is on the cuddy floor, but you won't need the wood blocks underneath the stainless step. My reinforcement under the floor is probably the same as yours except it has some fiberglass wrapped around it, don't know why.


I guess the fact that the cuddy floor is a solid sheet (except in my case) of 1/8"? fiberglass afixed on all sides, there really isn't anywhere for the foot (step) to go as long as its firmly attached to the fiberglass and the subfloor step base holds up. And I assume futher that the mast step base under the floor is designed for the mast, sail and associated hardware "weight" which hasn't increased for all of our work, it's the lateral strength that is being tested by the new mast hinge dynamics. But is it really all that different?
The new forces are in 'shear' along the floor which means the size of the screws and how many and how widely spaced is what gives strength to the mast base position. The danger is when just a slight bit of looseness gets in then the joint 'works' to pull the screws out and the fiberglass floor will disintegrate around the screws. It might be worth an new access port and use nuts and bolts and fender washers.


The mast/boom relationship hasn't changed, the boom has always been there applying it's flex pressure on the mast. That's no different than the stock step up. I can see however that adding a coupling of any kind inside the cuddy could compromise the rigidity of the complete mast unit. That couplers gotta go and I need to at least replace that entire lower section with a solid one piece unit.
It should work for a while, but don't how long or if there's a 'warning' period. The mast section is a Dwyer DM284 about $12 a foot. http://www.dwyermast.com, I'd get one foot, cut the slot off, and stick it inside your existing sections with a bunch of aluminum rivets.


I really like your adjustable step,
Thanks, but it came with the boat. I can't find one online, and a suitable aluminum channel say 1" x 3" only come in 8' sections, about $25

and I'll probably look at doing something similar if not copying it altogether, other than I can't imagine where to get that erector set looking piece. (maybe my old erector set...)
Barring that, I think the same thing could be accomplished (in a non adjustable version) by distributing the lateral pressure over a larger foot. If I were to take even an round (or square) steel 4 x 4 electric box cover and bolt the step to it, and then screw the plate down to again distribute the lateral pressure over a larger (and more screws) area it should work.
That' exactly right, but personally I am uncomfortable with only 16sqin's, I'd probably go 6x6" or if using an a-frame 8x8".

I think you're comment about the significant pressure on the partner (cuddy blowhole) coming from your A frame lifting from the horizontal is valid, but if I'm doing more of the standard "walk it up from the back" mast raising, I don't think I'm seeing why that would incur any more pressure than the low mounted tabernacle. I guess there's about 2 ft more of a lever above the cuddy that I'm pressing against... so maybe.
Exactly! Good luck with that!

So that's forward pressure on the top of the lower mast section. I've got to go back in and look at the inside of the cuddy roof, but just thinking out loud, If Iwere to take a 1" piece of plywood, cut the blowhole out (tight) and then bolt that piece (as big and wide as it can be) through the cuddy roof, that would have to be enough strength to offset that extra pressure wouldn't it?
Yeh, my boat, and apparently GL's boat have that wood below the hole. but mine was never finished and is getting rotten. There will be some occational forces trying to pull the lower mast out of the cuddy like when you are trying to push the mast up or maybe if you drop it accidentally and you should think about that too. I wouldn't cut the wood right away though, maybe experiment with wedges first to see what the angle of the mast wants to be.



All this mental exercising is fun, but it makes my brain tired. I should have paid attention in my advanced mechanical analysis class... oh wait... I never took anything like that... Maybe that's the problem... Confused
Scott, you may be thinking you've bitten off more than you can chew because there has been a lot of info passed around very quickly. But it's gonna be a long cold winter, plenty of time to accomplish you goals. It's fun for me and I hope it's fun for you! We'll help you as you need it, but you seem to have the right stuff!

[jdoorly]

I just found a source for 6061 aluminum channel 3" web by 1.5" legs $0.61 per inch:
http://www.speedymetals.com/ps-2218-12-141-x-017-x-3-170-channel-6061-t6-aluminum-extruded.aspx

Get a 6" piece, drill some holes in the legs and through the mast and install a 1/4"x4" pin or bolt, put a half dozen screws through the web to attach to the mast step*, and you have an strong adjustable mast base.

*I've said earlier bolts and fender washers are better if you have access.

[hectoretc]

I just found a source for 6061 aluminum channel 3" web by 1.5" legs $0.61 per inch:
http://www.speedymetals.com/ps-2218-12-141-x-017-x-3-170-channel-6061-t6-aluminum-extruded.aspx

Get a 6" piece, drill some holes in the legs and through the mast and install a 1/4"x4" pin or bolt, put a half dozen screws through the web to attach to the mast step*, and you have an strong adjustable mast base.

*I've said earlier bolts and fender washers are better if you have access.

Thanks jdoorly, I appreciate you scouring the internet for me.
I need to think if there's anything else I can possible build becuase the 6" of aluminum is $3.50 and the shipping is $12.75. There must be something else I can build...

I'll have to browse the website and see what else they have. I could make a couple motor mounts, I still want to do the cuddy hatch (top part) and door, need a swim ladder... what does a mainsail furler look like? (see... now you've got me thinking about that too...), oh a bow puplit would be nice.

Thanks again!

[hectoretc]

Mast hinge installed this weekend!



I think it went very well. Can't stand the mast up because my boat is put to bed for the winter in the deep corner of our pole shed packed in very well, but with the entire mast & footpiece out laying on the floor, it all seems like it's going to work great. The sections piviot on the lower bolt and nothing hits. Very firm junction, zero play anywhere.

jdoorly, I took your advice and went with the 3" wide aluminum stock for the side pieces so I wouldn't need to make the curved lower bracket/stop. I really like that Metals-by-the-inch place. I ordered the pieces pre-cut and it worked perfect- like a kit. Unfortunately, the mast is about 1/8" short of 3" deep so there is a little space between the lower cross member bracket (the 2"x3" piece) and the stern side of the bottom section, but it will still work for a "too far" stop, and once I get outside in the spring and get the mast aligned, I can drill two more holes in the face of it, and put in a shim to make it a perfect fit.
As always, I have a few more questions for you.
1- What did you use to plug the two ends of the mast. It looks like it might be simply troweled in BlackJack or maybe a Rubber compound of some sort, or did you actually machine some black plastic plugs?

2- What is that connector on the side of your Hast Hinge joint for?

Regarding your mast gallows, I can see from the third picture (anchor rope spool detail) that you have a cross support across the seats that looks maybe to be a 1 x 4, what did you make your verticals out of (2 x 2's ?) Also sort of looks like the whole thing is held in place by the feet fitting into the cockpit drain floor indent.
3- Is there any hard attachment at the floor or transom, or is it just held in place by the mast/boom friction?
4- Is the port side mast support (higher piece) adjustable? It looks like it's on with a wing nut or two.
Thanks again for all the help

[algonquin]

hectoretc - When I installed the DR Marine Tabernacle on Feather I filled the lower section of the cut mast with spray foam insulation. It makes it quite buoyant. Also I disassembled all the hardware on the main mast portion and then reassembled it using silicone sealer so the mast is essentially air tight and will provide some buoyancy if I ever flip the boat. This is something you may want to consider once you come up with a base plate to close off the main mast section. Brad

[hectoretc]

hectoretc - When I installed the DR Marine Tabernacle on Feather I filled the lower section of the cut mast with spray foam insulation. It makes it quite buoyant. Also I disassembled all the hardware on the main mast portion and then reassembled it using silicone sealer so the mast is essentially air tight and will provide some buoyancy if I ever flip the boat. This is something you may want to consider once you come up with a base plate to close off the main mast section. Brad

Thanks Brad,
That reminded me of yet another question I was going to ask. My mast appears to have what can best be described as a 1/4 section of a round rigid foam "tube" inserted into the full mast, floor to top (looks to be about the size of a pool noodle I guess). I suppose the very best test of mast floatation would be to take it off the boat and lay it in the lake to see if it floats, but I'd meant to aks if others have this same floatation inside their masts and had any positive/negative comments on it. I've not thought to get a picture of it (amazingly) so I'll do that and post it as well.
How did you go about filling the mast with spray foam so that you are sure it all filled. Or maybe it's not important that it entirely fill the mast, but just cap a couple feet at the ends so any airspace is secured in the center?
Thanks, Scott

[hectoretc]

On the mast/floation topic, Brads comments reminded me that I was reading some older posts and had come across a discussion of mast floats etc. that I wasn't able to finish, and now can't find again. There was a lot of math that I wanted to re-read more carefully, but associated with that, while scrutinizing jdoorly's photos on his mast gallows, I noted this picture in his gallery;

Did this end up working out as expected? What (if there is one) is the end result of the masthead floation thought conference? Yea or Nay or something in between? (will it float?)
Thanks, Scott

[jdoorly]

Hi Scott, please forgive my non-responsiveness; we had a little weather that made shrubs out of trees and grass out of shrubs, knocked out power, tv, internet and reminded us how fragile everything really is.

Good job on the tabarnackle! But it looks like you didn't use stop nuts- so your going to have to keep an eye on the those nuts. Glad you used 3" wide side plates and plan to shim it.

I used 'minicell' foam. It's an expensive closed cell (waterproof) foam that is easily worked with a japanese saw and rasp. I used to make custom kayak seats and kayak bulkheads (no hard spots) out of it and have a lot leftover. The plugs are about 2" deep and work extremely well to keep rain out. I'm sure there are all kinds of cheaper adequate materials. How 'bout wood?

The mast originally had, and the top of the mast stills has, a device for keeping out water that has 4 aluminum plates that are the shape of the inside of the mast but are maybe 1/16" smaller. Between each pair of plates there are rubber gaskets that are the same size. But, when you turn the screw, which is in the middle of the plates and fastened through a captive nut on the last plate the gasket material squeezes out along the perimeter and makes a watertight connection. I rebuilt mine and substituted neoprene for the gasket material. Take off the masthead fitting and see if you don't have one already in there. But also take Brad's advice and silicon, or otherwise, seal the mast so it floats- though certain (bad) conditions can render many safety devices useless, you should never put yourself in the position of looking back and saying I should have...

The connector lets me take the mast away from the boat, the wire is for the AWI (apparent wind indicator) that tells the direction and speed of the (apparent) wind. Suppose your sailing on a 'beat' (i.e. your coarse is 45 degrees from the 'true' wind direction. The AWI will read about 30 degrees. That's because 'true wind is just true wind, but 'apparent wind' is effected by (or added to) your boat's speed/direction vector. Apparent wind is what your sails interact with.

First, I always expected to box in the after 1 1/2 ft of cockpit and use that framing to support the gallows, so that cross piece is temporary, though it is adequately strong. However, I'm now thinking of reducing weight in the ends and have made the gallows so I can easily pull it up and out and keep the gallows in the car when I go sailing (only its weight hold it in place). The feet are captured by matching squares in the cockpit drain, and there are "U" shaped metal on the cross piece which the legs go through.

The extension for the mast (the mast sticks out a lot so I added the extension to increase mast height when trailering) is not adjustable but could be made adjustable by drilling more holes. The extension works the same as the tabarnackle with a lower pivot and a safety bolt above it. The extension swings down and out of the way of the boom when sailing.

The gallows legs are 1 1/2" x 1 1/2" x 42"(?) oak, your boats probably different. You have to go sailing and check the height of the boom when pulled all the way in, then deduct a few inches for clearance.

The masthead flotation project is on the back burner for now. I didn't like the wrinkles it seemed to cause, the wrinkles started in the main at the flotation and went several feet towards the center of the sail. I tried to fix the problem by incorporating a 3mm thick piece of plywood, the same shape as the flotation but an inch bigger, thinking that would stretch the wrinkles out. It didn't and I took it off to see what the mainsail looked like without it. It had wrinkles! So, having no more solutions at hand, and a bunch of other projects, yada yada yada.

My flotation provided 16 pounds bouyancy, the standard flotation for the Flying Scot is 30 pounds. My flotation is very thick but concentrated and on both sides, the FS's flotation is an inch or less thick and is more flexible but covers a lot more mainsail

[hectoretc]

Hi Scott, please forgive my non-responsiveness; we had a little weather that made shrubs out of trees and grass out of shrubs, knocked out power, tv, internet and reminded us how fragile everything really is.

Thanks Jdoorly, sorry you had the bad weather. In my other (real life) I work for a company that produces Outage Management software for Utility Companies and so many of our customers (ConEd, United Illuminating, Northeast Utilities) in your area reported lots of substantial outages. Weather keeps life interesting...

Good job on the tabarnackle! But it looks like you didn't use stop nuts- so your going to have to keep an eye on the those nuts. Glad you used 3" wide side plates and plan to shim it.

Agreed on the nylon centered nuts for the mast. I have them, but I just tossed it together for the "smoke test" knowing I was going to assemble and dissassemble it a dozen times before putting it on for good. Thanks for the watchful eye though, that could certainly be a failure point. I came to realize that I had mounted the 2 x 3 plate too low on the slot side. The mast will rotate to 90 degrees before the lower mast and 2" plate touch, but I'm going to move it up another inch or two so that if necessary, I could lay the mast down on the transom without hitting that plate.

I used 'minicell' foam. It's an expensive closed cell (waterproof) foam that is easily worked with a japanese saw and rasp. I used to make custom kayak seats and kayak bulkheads (no hard spots) out of it and have a lot leftover. The plugs are about 2" deep and work extremely well to keep rain out. I'm sure there are all kinds of cheaper adequate materials. How 'bout wood?

Thanks for the guidance, I'll dig through my garage and pole shed. I probably have something I can use there too. Also thanks for the heads up on the potential mast seal at the head. I'll check that out as well.

The gallows legs are 1 1/2" x 1 1/2" x 42"(?) oak, your boats probably different. You have to go sailing and check the height of the boom when pulled all the way in, then deduct a few inches for clearance.

I've started thinking about the simple X crutch I made to hold the boom up when I first raised the mast sans sails (pre-topping lift). That was before I'd come to understand that type of crutch came standard with many DaySailers. Had you considered a taller X for a mast crutch and discarded it based anything, or was the gallows your intended solution from the start? I could see a high crutch with a cross piece (sort of a capital A with a crown.) supporting the mast in the V at the top of the assembly, and the boom on the horizontal bar (notched to fit).
I'll probably try that first as it would be light weight and foldable (to keep it in the boat) unless you've already gone that way and discarded it for safety or structural reasons.

Unfortunately, right now my boat is about 4 inches too far back in the pole shed so I can't install the mast in the down position (so close). In the rightmost picture above, the top of the mast is sitting on a pile of stuff on a high storage shelf. The DS is in at the perfect angle and packed in so tighly (about 2" of hull to hull clearance to our speedboat) that there is simply no way to juggle it around to gain that tiny extra room I need to bring the mast level for testing. Later this winter, I'll either start moving the stuff in front of it (a day or two project) or actually push the boat back 6 inches, and jack up the trailer axel to move the back wheels 6-8 inches to the left so I can gain enough hypotenuse play with the crutch ideas before spring as well.

[jdoorly]

The main complaint with an "X" crutch is that it can slip and fall. I prefer the even simpler paddle crutch to that cause it's firmly attached. The worst crutch I've seen was on our Morgan 24: An 18" piece of wire crimped to the backstay and a snap shackle, like a short topping lift. Don't attach it to the boom unless the mainsail's down! Kinda defeats the point.

Anyway, I chose the gallows for its strength and usefulness. The boom stands solid on it, unlike with a topping lift which can sway around even with the mainsheet taught. The mast is quite a bit heavier (and longer) than the boom and there are stronger side forces while trailering, so strength is good. However, strength can be had without oak and mahogany. I've thought about bending up aluminum tube, which is far cheaper than stainless, but I'm saving up for the tube bender ($99 at Harbor Freight). I'd like to make handrails too, like on the Potter's, and re-do the pulpit/a-frame in aluminum, (the boat needs to go on a diet!)

We have some lovely weather coming, too bad the boats stuck in the snow!

[hectoretc]

Hi Guys,

I received my 1 ft of mast section that I'll cut down to make the mast joining insert and my new boom casting, but my question tonight is about the casting.

The original was held on by 3 rivets. Would you suggest installing the new one with rivets as well, or drilling and tapping the holes to use 1/4-20 machine screws?
There seems to be a mix of each on the boat so I'm not sure if that's based on stress points or just however the company that made that piece, well, made that piece.
Thoughts?

Questions on cutting the mast section into an insert upcoming after I stare at it a while.

Thanks, Scott

[TIM WEBB]

If I had it all to do over again, I'd drill, tap and screw. With good lock washers of course. Seems to work just fine for the mast hinge, and the joint is basically the same. Can't see any reason why it wouldn't work for the forward boom cap as well. In fact, I'm thinking about a fixed gooseneck, so in order to do that I'll prolly need to dig that thing out of the boom again to remove the "guts" of the roller reefing gizmo. If I do, I'll definitely drill, tap and screw to re-install ...

[hectoretc]

Thanks Tim,
My thinking too, and recent experiences support that if I've taken something apart once, I'm likely to need to do it again.
Thanks for the input!