Old Mast Jack Setup... Is This Broken?

[UncleHippie]

Hi Everyone,
I am fixing up my old '59 DaySailer and have a question about how the mast jack mechanism is supposed to be attached. I have only had the mast raised and in use once which was a couple years ago before our world became very interesting. So I don't recall exactly what was going on around this piece, but I am pretty sure it was not as loose and flopping around as it is now.

I can tell that the pivot bolt it attaches to has been bent from years of use so I am sure that I have to replace that, however even once that is replaced I am questioning if there should not be more support under the jack itself. It would seem that little bolt is not strong enough to support all of the downward force of the mast and shrouds. When I move the jack out of the way I do not see any kind of backing plate or block of wood that it would have rested on so I am a little puzzled. I am waiting for my new Dremel tool to be delivered so I can cut the bent bolt out of the way and then perhaps I will be able to see better under the housing.

Looking through my phone gallery I guess I forgot to take a picture of it, but I did record this video to show what I was looking at. Would love any additional information on how this is supposed to be configured. Sorry for the shaky camera work
https://youtu.be/8gFQKeWViBA

Thanks

[GreenLake]

One look at the thumbnail picture from your video and I would agree that this "isn't right".

Yours looks like it is meant to travel inside some support hat has a slot, so you can adjust mast rake. The screw is just supposed to hold the mast position, not the weight.

Mine has a different plate, not the round one like yours but square so it sits on the verticals of the keelson. I've never removed it, so I don't know what the underside looks like. But there also is that screw.

[UncleHippie]

Thanks GreenLake,
I was able to pull the bolt out last night and get a better look at it. There is definitely something missing. I agree that this setup looks like it should slide to adjust mast rake but there is just one single hole and an empty void under the keelson. And because it has been used in this configuration for what I imagine is quite some time the bolt has caused damage to the mast jack. You can see in the pictures below that it has blown out the side of where the bolt goes through. There is a small section of the keelson around the opening that also has week fiberglass, which will probably need to be fixed. Plus with all of that weight on the bolt for who knows how long, I am wondering if the glass where the bolt was supported is structurally sound.

My initial thought was the mast jack was probably original, it seems to have that late 50s look and feel to it. Then at some point they re-worked the keelson but did not set it up correctly.

However, the keelson itself looks to be original fiberglass work as it seems pretty solid and the transitions to the hull seem solid.

Comparatively, there are signs of poor fiberglass work around the cb trunk and under the cuddy. It looks so bad it reminds me of plaster of Paris ... It looks like someone just dipped some fiberglass in resin and the layed it down and left it... oh and then painted over it... no prep work what so ever and no sanding afterword... so that is all peeling up.

So perhaps they just tried to find another mast jack that would work and set it up in this bizarre way. I can't imagine someone thinking that a 1/4" bolt could support all of that downward force

Based on all of that I am not confident in trusting the previous work that was done to this boat... so unfortunately it looks like this project just became much more involved than I was planning. I know that is par for the course in boat repairs but still frustrating when I wanted to get her back in the water pretty soon.

Either way I have to decide how I am going to engineer a solution for this keelson and mast jack. I think the mast jack itself could be salvaged if I have someone drill another mounting hole on the opposite end... it seems to be symmetric on both ends.

Not sure there is room to glass in a support structure under the keelson without opening that up some more.

Perhaps there is a way to retrofit something on top of the keelson to replicate the system that you have setup?

Going to think through this some more while I work on other aspects of the project.

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[GreenLake]

Where should I start?

Trust. Obviously at some level, we never trust anything we didn't do ourselves. On another level, the more you can sail the thing, the easier it is to separate must fix items from ones that may work better than you have a right to expect.

The keelson in these boats may have been built around a wooden member, and not as a hollow channel. In that case, there may have once been something on which to rest that mast jack. (I agree that it looks the correct vintage). Now, as to your planned repair.

Drilling another hole at the opposite end sounds like a fine solution. (But, remember, you don't need to reuse the same holes in the fiberglass, they can switch ends as well ...) Have the same shop make a short length of a shallow bronze U channel that fits snugly like a cap over the keelson and is long enough to go past the edges of the circular hole. Have them cut a rectangular slot, and drill it for the same bolt. That should be enough to distribute the weight and by having the bolt pass through both the flanges of the U channel and the keelson you keep everything from sliding around.

(If you think the walls of the keelson aren't the strongest any longer, just extend the "cap" another +/-1/2" front and back: that should make it so enough of it rests on reliable fiberglass. If you think there's a large amount of damage, you may have to re-build a section of the keelson over a big of a foam core - anything to give it that square cross-section. But it's work, and you'll need the "cap" anyway.)

Now, if the addition of the wall thickness of the the support (about 3/16" would seem like a ballpark) eats too much of the adjustment range of your mast jack, you may need to lengthen the stays. If they are fixed length, and 3/32 go replace them with 1/8" (that's recommended practice) but get the ones that are adjustable when not under load - DR Marine sells that upgrade - contact them by phone to find out what measurements they need.

If some PO did that upgrade already, you may be fine. In either case, a mast jack is more convenient than the full "turnbuckle" type stays, so no need to support adjustments under load.

PS: the mast probably sits on the hull right now, which is plenty strong at that location in a DS.

[UncleHippie]

Thanks for the new outlook. I was pretty frustrated when I first found all of this, but I agree it would be good to fix the necessary safety issues immediately and then assess what else is needed after getting it out on the water several times. Obviously the mast jack needs work. I believe the sides of the keelson are solid and in good condition, it was just a small piece around the opening that was loose, so a bronze cap seems like the right solution here to distribute the weight.

The standing rigging does appear to be original or at least it is the 3/32 size so I was already planning to upgrade that. I have seen other posts recommending talking to Rudy at DR Marine so I will do that once I have a workable solution with the mast jack if I need adjusted lengths.

[GreenLake]

That's fairly typical and a reason to take things in chunks: fixing the mast jack support may slightly alter the dimensions needed for standing rigging. By taking these in order, you avoid purchasing the wrong size upgrade. However, that also means, the moment you put your mast jack fix in, you won't be able to raise the mast until you have the new stays.

One thing to consider. Rudy sells stays that are adjustable (those are the ones I got for my upgrade). Unlike true turnbuckles, the adjustable portions would be set before you raise the mast as the tension comes from the mast jack. If you measure your stays now (assuming that you can tension them fully, you may be able to figure out how much (if at all) the new length would differ (approximately, and based on your planned repair). Rudy may be able to sell you some where the adjustment range covers the likely final length so you would be able to do fine tuning of the length by the adjusters, and after you lock in that adjustment treat them like fixed length.

That calls for placing your call to Rudy early, so you can get your new stays figured out and shipped so you have them right away after your repair is finished.

Also, you might want to check how much travel there is on the mast jack as things stand today. As you lower the mast jack, there comes a point where the tension in the stays is fully released (and you can easily connect/disconnect them). Lowering the mast jack any further wouldn't be necessary but it may be possible to do so on your boat. If there's any "extra" travel, that can be subtracted from any increase in height of the mast step.

I'm thinking, if there truly was something that collapsed below the mast jack, it may have been compensated for by raising the jack a few extra turns. Don't know if you can picture that and whether it applies, but if there's extra, the goal wouldn't be to allow the new stays the same number of turns on the mast jack, but simply enough turns to get from zero to full tension (and perhaps one or two spare turns, no more).

[UncleHippie]

Thanks GL,
This is exactly what I was thinking. My plan is to find a temporary 1/4" bolt that I can use to "install" the mast jack as it had been previously set up and see how high it sits and how much slack I have in the current stays. From there I can assess how much the cap would offset this and go from there.

Yes it is very possible that there was considerable compensation being made for a collapse considering how bent the bolt was so I may not have to adjust the stay length... we shall see. I will report back when I know more.

[GreenLake]

Sounds like you have a plan!