Hi all, I have decided to rebuild the front crossmember to my prindle 16, because there was some movement when sailing. I have it all taken apart, except for the v-bar, which is completely frozen on each end. The 2 nuts on each end are removed, but the bar is so tightly frozen it feels like it is threaded. I am reluctant to mess with the bolts, although I could get at them from inside the crossmember. Does anyone have any suggestions, or know how this is assembled?

Thanks all and stay well,
Paul

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Paul
Prindle 16
"Nuissa"
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Have you disassembled the dolphin striker yet? The brace is under tension at the striker, and until those bolts are relieved, it may be binding. Dolphin striker adjustment is shown on page 35 of the manual here https://www.slosailandcan…/Prindle151618Manual.pdf



Edited by tominpa on Dec 06, 2020 - 03:44 PM.

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Tom
NACRA 5.7 (1984 Sail 181)
Pennsylvania
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Yes, that one took a while, but is removed. The only thing on the crossmember is the v-bar, which is stuck on the bolts at each end. The nuts are off, and I have tried wedging under it and using a little wd40, but it isn't budging.

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Paul
Prindle 16
"Nuissa"
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normally there are 2 bolts on each end and they are welded to a plate on the inside of the beam, not welded to the beam just the bolts welded to the plate. They can be difficult to remove if you find it necessary. You should be able to remove the end caps and look into the beam to see.

There has been quite a a bit of side pressure to the bolts over time making the bar difficult to remove

That is very helpful, thanks. It is just as you describe. I suspected the bolts might be welded, but did not know for sure. I am going to keep workinging with the bar to see if I can get it off.

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Paul
Prindle 16
"Nuissa"
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That's one of the best manuals for a beach cat I've ever seen!
You might have to compress the DS bar towards the crossbar with a ratchet strap just a bit to get the tension off.
Thread nuts on the ends of the bolts a little way to protect the threads and try tapping them out.

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'82 Super Cat 15
Hull #315
Virginia
Previously owned: '70 H14, '79 H16, '68 Sailmaster 26, '85 H14T
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njcatman

That is very helpful, thanks. It is just as you describe. I suspected the bolts might be welded, but did not know for sure. I am going to keep workinging with the bar to see if I can get it off.

My assumption is they are extremely corroded. I had some shear off while sailing... not a fun time. I would flip the beam upside down with the dolphin striker up. Soak the bolts with a corrosion inhibitor (I use Corrosion Block). After a couple of rounds, heat the bolts with at propane torch. Take a 5# sledge and beat the bolts out into the beam. Something to be careful of is compressing the beam inward while knocking the bolts out. Just remember stainless bolt with aluminum dolphin striker and aluminum beam with absolutely no corrosion protection at all when originally installed. Be sure you coat the new bolts with a corrosion inhibitor paste.

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Scott

Prindle Fleet 2
TCDYC

Prindle 18-2 Mod "FrankenKitty"
Tornado Classic "Fast Furniture"
Prindle 19 "Mr. Wiggly"
Nacra 5.8 "De ja vu"
Nacra 5.0
Nacra 5.8
Tornadoes (Reg White)
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I got it all apart. Thanks everyone for the assistance. In the end, a good soaking of corrosion inhibitor, some good cold weather, pushing down on the v=bar, tapping the bar and bolts and then driving some cedar wedges underneath did the trick.

The bar looks in decent shape, but the connections to the hull are not in very good. The port front inner bolt is bent and about half of the holes through the bottom of the crossmembers are oval shaped from movement. This boat did not have parallel rudders and it is now obvious why. I think I am lucky I never had a problem on the water (I was getting some unexplainable banging from the left hull at times).

My plan is to rebush the holes with 5/16" bronze bushings and then make a compression sleeve to hold everything in place. Everything will be lined up and tight. I don't think it will be very difficult, but of course, any suggestions will be greatly appreciated. I am prepping this Prindle for its next 40 years!

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Paul
Prindle 16
"Nuissa"
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Be careful of mixing metals since you are on saltwater. Aluminum readily corrodes and gives up electrons to metals like bronze. If you can find aluminum bushings or spacers, they may be better since you are on saltwater and will solve your wallowed out holes without putting dissimilar metals in direct contact. I have a monohull sailboat that had some wallowed out holes in an aluminum rudder head, and used aluminum spacers with a 5/8 outside diameter and 3/8 I.D. that fit the the 3/8" stainless bolt perfectly. With saltwater, there is a galvanic potential between aluminum, and other metals that are lower on the galvanic chart. That may have been part of the corrosion you found. Aluminum alloys are at -760 to -1000 on the galvanic chart, and bronze is way down the chart at -340, which would make these a bad combination in the long-run. Without getting into it too deep, just look at Table 1 of this article https://www.boatus.com/se…marine-corrosion-101.asp

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Tom
NACRA 5.7 (1984 Sail 181)
Pennsylvania
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I have been reading about marine grade bronze bushings, where they add aluminum to the mix to reduce corrosion. You have me thinking, though, that I can do it in all aluminum. I can buy 5/16" ID x 3/4" OD spacers that run from the fiberglass deck to the underside of the top of the crossmember. Basically, it will be a 3/4" diameter solid aluminum compression fitting in the crossmember, with the 5/16" bolt going through it. It means making larger holes in the crossmember (3/4"), but it will hold much better than the original. If all goes well, it will be stronger, easier and cheaper. The spacer will need to be in 2 piece to get it in, but the bold will hold it all together.

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Paul
Prindle 16
"Nuissa"
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njcatman

I have been reading about marine grade bronze bushings, where they add aluminum to the mix to reduce corrosion. You have me thinking, though, that I can do it in all aluminum. I can buy 5/16" ID x 3/4" OD spacers that run from the fiberglass deck to the underside of the top of the crossmember. Basically, it will be a 3/4" diameter solid aluminum compression fitting in the crossmember, with the 5/16" bolt going through it. It means making larger holes in the crossmember (3/4"), but it will hold much better than the original. If all goes well, it will be stronger, easier and cheaper. The spacer will need to be in 2 piece to get it in, but the bold will hold it all together.

Something you may consider is adding a section of aluminum inside the beam as a backing plate also. When you do install the bolts, us a good corrosion inhibitor paste/gel. I use Lanocote and Tuff Gel.

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Scott

Prindle Fleet 2
TCDYC

Prindle 18-2 Mod "FrankenKitty"
Tornado Classic "Fast Furniture"
Prindle 19 "Mr. Wiggly"
Nacra 5.8 "De ja vu"
Nacra 5.0
Nacra 5.8
Tornadoes (Reg White)
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The aluminum bushings are less expensive anyway, and plenty strong to get your through the next 50 years. By then, it won't much matter. I had to use a drillpress to put in the 5/8 spacer that fit exactly to the rudder head, but it's a perfect pivot point. You don't even have a moving part.

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Tom
NACRA 5.7 (1984 Sail 181)
Pennsylvania
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