Tabernacles - Mast Hinge

[TIM WEBB]

No prob!

I think you'll find yourself doing that more and more as you continue to make the changes to your boat that make YOU happy ...

[hectoretc]

There is a standard method for lengthening a mast section. Mast makers, like Dwyer, can only get mast sections up to 25(?) ft long and must therefore scarf sections together to make long masts. What they do is take an extra section of the same mast profile about 10% of the total length of the mast, and cut away the slot area (after 20% of mast). The scarph section can now be folded in a little, but it's enough to slide half into one mast section and then the other half into the second mast section. Then put in a lot of equally spaced pop rivets in to hold it together and spread the load.

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.

Jay, having purchased my foot of DM284 extrusion from Dwyer, I'm getting ready to cut said slot off using my handy rotary disc saw, and form the insert for the mast.
Just want to check my compass as my recent experiences have been "gee... I cut it three times and it's still too short...".


Are the red cut lines pretty much in line with what you were suggesting? I'm assuming I need to cut "out" the full channel so the section can be collapsed enough to fit inside the upper and lower sections of mast. And them am I correct that rivets are the recommended attachment rather than screws? And I'm assuming too many rivets are better than too few.
Again just measuring twice and cutting (hopefully) once.
Thanks, Scott

[jdoorly]

Scott you have the concept perfectly. The only thing I might add is that when you start pushing the 1 foot section into the mast sections; if it doesn't slide in easily enough or if it slides too easily you may have to clamp it a bit to compress it like piston rings, or spread it a bit so it fits tightly enough for the rivets to grab.

Personally I would use aluminum rivets for this job since your not relying on only 2 or 3 to hold up the mast, like on a stay. Aluminum rivets are much easier to install with a manual rivet tool and are galvanically the same as the mast so you won't get corrosion. Steel rivets will rust, and stainless rivets need some heavy duty muscle with a manual riveter (and they will corrode due to galvanic electrolysis). Take a look at your mast, I think you will see that the rivets are holding fast after 40 years but screws tend to 'eat' aluminum over time. As you know from your hinge project thru-bolting is also quite sturdy as well as maintainable over time.

Thanks for the quote credits but you missed Greenlake's contribution.

[hectoretc]

Mast stub assembly - mission, to reassemble the two halves of the mast previously cut to accommodate a tabernacle.



Started with 12" section of DS-284 mast from Dwyer, measure out about 3/8" from the inside slot channel to insure when this section is compressed and inserted into the mast sections, it will not hit the mast slot channel. In hindsight it looks like I could have gotten away with 1/4" but I didn't want to cut it twice, and had no idea how to do the math to figure it out accurately on paper.
I cut this using a reciprocating saw because my roto-zip cutoff tool died. (just in time for Christmas).
As jdoorly suggested above, but not having a ring compressor, I used two small bar clamps to compress the sleeve down so it would fit inside the mast halves (one end at a time).


Mark 1/2 way down the sleeve (6" in my case), and insert it into one end of the mast, tap it in, release one of the clamps, tap it in some more (rubber mallet), release the 2nd clamp and finish tapping it in 1/2 way.
Repeat for the other end. If you've done too good of a job compressing the sleeve and it isn't extremely tight in the first section, you may want to drill and insert a rivet or two to keep the 1/2 way mark in the center when you insert the 2nd end.
I have no idea how many rivets are enough, but I assume more is better than less, so I did three parallel rows of 6 aluminum rivets , one at 1", 3" and 5" up each side.
I expected this to be a small issue, and it was. The rivets did not want to easily slide through the cuddy partner (blowhole) so I had to trim out just a little fiberglass to let the rivets through. That is why I put them in even rows so I'd only need three trim cuts. It doesn't need to be much trimmed out as there is always a little slop in that fit.

The completed seamed mast stub now installed. The seam is extremely strong (I could stand on it between two sawhorses and there is no flex at all)
Total time from first pencil mark to finished installation, 90 minutes +/- 5 minutes, and that included realizing my rotary saw was dead and that I needed to dig out the sawsall.

Questions... comments... GL and Jay, do you think 9 rivets per half is enough (18 total)? Overkill, need more?, it just seemed like a round number and it was symmetrical.

Oh... and the ice all melted back off the lake in our 45-50 degree weather over the past few days so my countdown to ice out (T-141 days - approx 15-April) is on hold...

[GreenLake]

Nice pix.

The way you did your internal sleeve, I'd say it gains most of its strength just from wedging in the profile. The rivets would seem like icing (almost). So, if anything, I'd vote for something nearer the overkill end of your range of replies.

Being able to hold your weight should be a good sign.

[jdoorly]

Scott- another great job masterfully done. 9 rivets each sounds about right, The standard pattern would be more of a random zig zag to prevent stress cracks from propagating, but you had a good reason for lining them up. I'm sure it will outlast all of us. I didn't realize the blow hole diameter was that small, mine is missing the built-up boss around the hole and I have oodles of room. You might be ok without adding partners, or maybe just putting in 3 wedges between the mast and the hole.

Just for the record, what size and type were the rivets? Manual or pneumatic? What are you gonna do about strengthening the mast base?
And again good job! (and pictures to prove it!)

[hectoretc]

Just for the record, what size and type were the rivets? Manual or pneumatic? What are you gonna do about strengthening the mast base?
And again good job! (and pictures to prove it!)

Thanks Guys - I used 5/16" Aluminum pop rivets (biggest I could find at my local hardware store). The way I had to pound the sleeve in (sleeve is probably the wrong word, sounds like an outside the mast word) it was pretty snug.

I was going to ask you guys some more about the step.

I was able to jockey the boat around in the pole shed so I can get the mast installed the way it's supposed to be, and for the purposes of holding it up, fashioned a quick x-crutch stand out of 1 x 4's. The smaller boom crutch is my original 1x2 crutch I made when I first got the boat last August.

(pardon the mess, we're remodeling)
This is a lousy picture, too dark on my iPhone, but it works for my question.
When I put the mast in the x-crutch, which I assume will be a similar loading no matter what I end up building, I find myself questioning where the center of gravity is on the mast, and wondering about the dozen or so feet of mast hanging off the back. The transom "appears" to be almost at the length center on the laid down mast.

Jay - have you noticed when trailering that the mast head bounces up and down much? It seems (while looking at it in the barn) that it might, and I should think that any down bounces at the masthead will be echoed in reverse at the hinge point (sort of a standing wave), trying to tear the step out of the floor. Depending on your response (or on my early experiences next spring), I'm thinking I may fashion a long support pole from the mast head to the rudder gudgeons to stabilized it and keep it from bouncing. Also a strap over the mast at the hinge should help prevent it from oscillating and trying to lift the post out of the step. (if needed)
- (jdoorly's mast step)
Although I know I don't understand the dynamics of mast raking (is that the fore-aft tilt?) I'm also nearly certain I'm going to purchase the 3x6 aluminum channel and reproduce the mast step base that you have in Desperado. If for no other reason than (as you mentioned previously) it will give an 18 sq inch plate to distribute the weight and pressures. I am able to get under the cuddy floor for bolts and larger fender washers via the damaged floor section I cut open to repair. Confirming the obvious here, there are no screws down through the mast step, just the pin (stainless?) through the channel and the horizontal hole in the mast and step foot (correct?).
Lastly, I am also nearly certain I'm going to install approx 12x6 piece of plywood or something as a partner stiffener under the cuddy roof around the mast hole. I can secure the mast with L brackets to the wood providing yet another support point, and I need a wood surface there for some other items that need attaching anyway.
It seems to me I had another question from this weekend's work, but I've lost it in the course of this posting. Oh well, there's always tomorrow.
Thanks all, I continue to greatly appreciate the suggestions and expressed concerns.

[jdoorly]

Yes, my mast does overhang the transom a lot. (Since the standard mast is 20.5' from location B2 to the masthead, and the pivot is higher than that, if you deduct 10' for the length of the boom plus another foot to the transom that leaves 9.5 feet of overhand). It does bounce although I always tie it tightly down to the gallows. There are 2 reasons it makes me uncomfortable, it's old and beat up and I worry about it getting damaged, and it sits out pretty far behind the transom and I worry some car will not see my orange flag and hit it. That's why I made the gallows extension- to raise the end of the mast over 8' at the masthead end.

I can disconnect the pivot and pull the mast forward up to the pulpit and tie it down there, that cuts the overhang to 3 feet. Generally I don't do this because then I have to dig out a 3/4" box end and a 3/4" socket to unscrew the 1/2-13' pivot bolt. But next year I will try using the safety bolt scheme, one of those big wiggly cotters, and see if the mast does or does not need the firm fit afforded by the wrenches.

I've made a detachable roller for the mast on the gallows and a holder for the mast stub so the mast can be held in three places and 'rolled' forward to the pulpit.

A support pole would help, although I haven't bothered to try and support the overhanging mast. It might by better to use a short gin pole to put in some leverage angle and pull the main halyard over the gin pole and tie it to the foredeck cleat which would dampen any bouncing.

[hectoretc]

Yes, my mast does overhang the transom a lot. (Since the standard mast is 20.5' from location B2 to the masthead)

I keep reading terms such as "B2" and similar mast location references, and for all of my googling and reading of old postings, I don't think I've found a comprehesive explanation of these points. Can someone explain (please) what (and where) the various points like "B2" this are on a DaySailer mast?
Thanks - Scott

[GreenLake]

The answer is on this stie in the box below the logo.
Click on Day Sailer Association and then "Handbook" and then it should be extplained in chapter 3.

[hectoretc]

The answer is on this stie in the box below the logo.
Click on Day Sailer Association and then "Handbook" and then it should be extplained in chapter 3.

Ah-ha.... thanks... I've read that before, but didn't make the connection to the bands = B1 B2 etc. That makes sense (now)

Thanks again...

[hectoretc]

Yes, my mast does overhang the transom a lot. (Since the standard mast is 20.5' from location B2 to the masthead, and the pivot is higher than that, if you deduct 10' for the length of the boom plus another foot to the transom that leaves 9.5 feet of overhand). It does bounce although I always tie it tightly down to the gallows. There are 2 reasons it makes me uncomfortable, it's old and beat up and I worry about it getting damaged, and it sits out pretty far behind the transom and I worry some car will not see my orange flag and hit it. That's why I made the gallows extension- to raise the end of the mast over 8' at the masthead end.

I can disconnect the pivot and pull the mast forward up to the pulpit and tie it down there, that cuts the overhang to 3 feet. Generally I don't do this because then I have to dig out a 3/4" box end and a 3/4" socket to unscrew the 1/2-13' pivot bolt. But next year I will try using the safety bolt scheme, one of those big wiggly cotters, and see if the mast does or does not need the firm fit afforded by the wrenches.

I've made a detachable roller for the mast on the gallows and a holder for the mast stub so the mast can be held in three places and 'rolled' forward to the pulpit.

A support pole would help, although I haven't bothered to try and support the overhanging mast. It might by better to use a short gin pole to put in some leverage angle and pull the main halyard over the gin pole and tie it to the foredeck cleat which would dampen any bouncing.

I would think that dismounting the mast to roll it forward sort of negates the purpose of the high mast hinge (as I see it) which was to be able to leave the sail attached to the mast and "folded" over the boom. But I suppose, depending on how you did it, the mast slugs could slide in the mast slot as it's moved forward... it could work...

The lake I'll sail on for the first year is out back of my cabin and so worst I'll have to do is trailer about 500 ft from the public landing to my driveway if I (or my cabin mates) decide I'm not docking the sailboat all summer. We have (a few) other boats to park on our dock and I'll need to lobby for dock space. So far not everyone is as enthusiastic about my addition to the fleet as I am, but what the heck... Plus, I just bought a dozen 55 gal plastic drums and (in my spare time) I'll build a floating dock this winter and suprise everyone next year with lots of new dock space.
Our lake is pretty small (200 acres) but that should give me enough room to figure out how to go forward and backward and sideways properly. If it gets to constraining, I may trailer to the next lake over which is only 4 minutes from my driveway on a backroad, and that will be plenty big for me to play on for a while (1000+ acres), so I'll not really be doing much signficant trailering anyway.

[jdoorly]

The "B" stands for band, it's usually a piece of black electrical tape or black paint which is applied to the mast and boom to show the allowable limits of sail position and size. If you are racing and you look over at an opponent's mast and see that his mainsail is above B3 you can protest him (most people wouldn't notice or would let the protest opportunity go). See the DS Hsndbook picture 7.1 and para 7.4 thru 7.7: http://daysailer.org/pdf/dsbylaw3.pdf

About the mast step, understand that it's not my design, mine came with the boat when I bought it. It is stainless and uses 1/4" pin with circular cotters in both ends exactly the same as the Dwyer hinge tabernacle pins. As I recall the aluminum channel was a bit wider and definitely taller. Being wider, you may need some spacers to hold the mast in the center; I would use the white nylon spacers cut to length if necessary and cut a 20 degree slot in them and then 'snap' them on the pin. Being taller is a good thing. When my mast fell from a parted forestay the mast base tore out of the step because there was only about 1/8" of meat left at the bottom of the mast. the higher channel will allow you to locate the holes higher for better strength. Also, don't put the holes in in a straight line in the channel, make them curve up at the ends because with the mast in the middle it will lie flat on the step but as the mast moves away from the middle the it will pivot at the partners and the angle increase as it stands on one end the mast the hole gets higher.

Terms are getting confusing. Let's call the mast 'the mast', and the casting in the mast base 'the casting' and the metal channel which is screwed or bolted to the cuddy floor the 'mast step'. Yes the only thing holding the mast in place is the 1/4" pin that goes through the step side wall then through the mast, possibly through the casting depending on how high the step holes are, then out through the step's other side. You should check that the material under the cuddy floor is substantial to bolt or screw into, thicker is better.

Yup, the sail's slides slide back up the mast as I pull the mast pivot toward the pulpit, but they can bind and require sailorspeak to grease them.

[hectoretc]

My mast base is a stainless "U" channel 6"x2 1/2" with five #10x4" ss screws holding it to the mast step (under the floor). It has 7 sets of holes in the sides which are used to set mast rake by putting a 1/4" pin through an appropriate hole, then though the mast base casting (the mast), which needed a hole to be drilled in it, then through the opposing hole and cotter pinned. That came with my boat. But I modified it and it's still in prototype and I'm still working out the bugs. This was originally an attempt to raise the mast so I could rake it more to gain weatherhelm. I kept adding 3/4" blocks plus a wedge block so the end of the boom wouldn't hit my head! Now it is approching instability in athwartships direction- it needs to be wider, but maybe I'll spring for a 4' section of DM2 or make a 'big' sailboat type tabernacle. Don't know yet.

I had to make a stop at my local Home Depot this morning, to pick up the dbl 2x10 joist hanger for my CB uphaul project, and since I was there I did as I sometimes do, and scan the hardware section for solutions to completely unrelated problems. Lo and behold, look what I found...

This is a 6x6 wood post base but it struck me that maybe, it could also be an adjustable mast step plate. I also saw a 6" x 8" mending plate, both of these are fabricated from 1/16" galvanized steel. I pulled up D&R's website on my iPhone and verified the width of the DSII mast to insure it would fit, and bought these pieces as well. The mast fits perfect. The edges are 3/4 high so I should be able to get some good purchase on the base piece and through the mast itself. It's pretty wide, so I'm not sure if I'll have to get a 6 1/2" long pin to go through or more likely drill into the sides of the mast and base, tap and insert a long screw through each side.

Jay - I'm remembering what you said about drilling the side holes in a smile as the base will lift slightly when tipped.

More to come... Scott

[hectoretc]

Finally got my boat outside where there is enough head space to raise the mast.

Unfortunately, I didn't think to take a picture with it up, but we've all seen sailboats with their masts up. The mast hinge worked fantastic (thanks jdoorly!). There was absolutely no sway or discomfort that it was going to fall. I hooked the main halyard to the headstay chainplate, started at the back of the boat, walked the mast up hand over hand moving forward toward the cuddy until there was enough angle on the halyard to help it up, and shooop... up it went. I slipped in the bolt/pin and there it sat, stable as a rock.

Picture from this winter in dry dock

Unfortunately, with all of the modifications, cuts and reassembly this winter, I think I lost about an inch of mast height, so my sidestays were very loose. After tightening them all the way to the stops, the sidestays are firm, but I don't think they have any where near whatever the torque is supposed to be on them. There is a lot of available tightening adjustment in the headstay, but that will change the rake of the mast, which I know nothing of. I'll need to re-read the postings on adjusting the stays, but I'm thinking I'll likely need to install a spacer between the step and cuddy floor to get a little more adjustment in the sidestays.
Lesson for next time... think twice, cut once.