Dolphin striker rod loose :: Catamaran Sailboats at TheBeachcats.com

Dolphin striker rod loose

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Andinista

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Posted: Feb 20, 2022 - 08:37 PM

The dolphin striker rod is a bit loose sideways on the front beam. The holes have grown a little bit, I don’t know when it happened, I just realized now, they are probably like that since quite a while. Any body has had this issue? Should I be concerned? I have an old beam from where I could cut a piece to reinforce the whole section, with holes of the proper diameter. if I do that it wont be soon, I’ll still sail like that for while.
tominpa

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Posted: Feb 20, 2022 - 09:59 PM

I have seen dolphin striker rods bend, but to be loose in the beam is a new one on me. They provide structural stability in the vertical direction, so it seems a bit unusual they would flex parallel to the beam, or that you could even perceive that with the striker properly tensioned to apply prebend or upward pressure on the beam. Either it has corroded, or was never properly tightened.

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Tom
NACRA 5.7 (1984 Sail 181)
Pennsylvania
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revintage

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Posted: Feb 21, 2022 - 06:12 AM

Have seen this on a badly corroded 18SQ beams with the front beam patched. Returned them and made new beams from 100x2mm. Made a good deal as I got two 5.8 hulls in exchange.

EDIT: Finally found the image of what was hidden beneath the patch on the 18SQ beam I received .

If the holes are so big that the distance tube falls out make a new that is 2x1,6mm longer. Add patches top and bottom made from the other beam. I guess 7x7cm cm is enough. A 4.8mm blind rivet in each corner should do. Then add larger and thicker 9/16" washers than before, that you round to follow the beam diameter. Lower the mast and the job will be done in half an hour, then sail on for the rest of the season. Don´t forget the beam pre-bend, I don´t know what the 5.5 instructions say, but I would go för 10-12mm.

Edited by revintage on Feb 21, 2022 - 10:03 AM.

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Brgds
Lars

Frankentri 5.8/5.5/Inter20
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Andinista

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Posted: Feb 21, 2022 - 12:23 PM

Thanks Lars and Tom. Yes, quite likely I may have some corrosion. I'll inspect with more detail next week. The two times I had to replace the rod before, on another boat, I wasn't able to remove the nuts, the threads were damaged, so I had to cut it. So I anticipate that I'll have to order or make a new one.
tominpa

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Posted: Feb 21, 2022 - 06:52 PM

There is a potential for galvanic corrosion, especially in salt water as the stainless steel striker rod, nuts and washers are in contact with aluminum. If you can get things loose, it might be a good idea to put some corrosion inhibitor at this location. This sounds like Deja-Vu with your bow foil problem where we discussed corrosion inhibitor on page 2 https://www.thebeachcats.com/forums/viewtopic/topic/18343/start/20

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Tom
NACRA 5.7 (1984 Sail 181)
Pennsylvania
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revintage

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Posted: Feb 22, 2022 - 03:42 AM

QuoteThere is a potential for galvanic corrosion, especially in salt water as the stainless steel striker rod, nuts and washers are in contact with aluminum.

Concur! It would also be a good idea to loosen the striker band from the beam and check for corrosion there, too.

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Brgds
Lars

Frankentri 5.8/5.5/Inter20
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Andinista

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Posted: Feb 22, 2022 - 05:27 AM

yes. I use tef gel in all my repairs since then. The bow foil was corroded before I moved the boat to the beach, it’s an old boat and now on the beach it will get worse. Maybe I should store it elsewhere during winter months to give it a break, I did it a couple times but it’s more hassle a money, I have no room at home for
It.
texastuma

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Posted: Feb 22, 2022 - 05:45 PM

From personal experience, I would pull the striker off completely and replace all the bolts. I had a boat fold up because of sheared bolts on a dolphin striker. I like TufGel, but I prefer LanoCote.

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Scott

Prindle Fleet 2
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Andinista

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Posted: Mar 03, 2022 - 10:25 AM

Unexpected findings after inspecting the dolphin striker:
I removed the nuts of the DS bar and the bolts are sticked to the beam, my hand doesn’t fit inside the beam to do much more, I would need to extend the wrench somehow. Maybe next time. Other than that, they seem solid, without visible signs of corrosion. I tightened them back.
The holes on the beam for the rod are about the diameter of the compression tube, so what happened was that the upper nut was loose and the compression tube’s upper edge was below the beam hole, so the rod had room to play laterally. When tightening the upper nut the compression tube fits in the hole and the rod doesn’t move anymore. The hole is ok, with all it’s thickness, I wouldn’t say that it grew because of corrosion. Maybe the previous owner decided to insert the compression tube from there?
The big problem is that the compression tube is stuck to the rod, I tried to move it by tightening the upper and lower nuts separately, with the other nut loose, without success. If I tighten both again the DS tension is about enough, I’d like some more prebend but can’t get it. Next thing I’ll try is to hammer the rod from the bottom to see if it comes out, not quite sure. I tried once but couldn’t. I’ll try starting with the upper nut tightened, to have the tube aligned with the hole. Otherwise I don’t know how I will replace the rod and tube when needed.
revintage

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Posted: Mar 03, 2022 - 11:29 AM

QuoteI removed the nuts of the DS bar and the bolts are sticked to the beam, my hand doesn’t fit inside the beam to do much more, I would need to extend the wrench somehow. Maybe next time. Other than that, they seem solid, without visible signs of corrosion. I tightened them back.

The three bolts are welded to an inside plate and is to be removed as an unit. If it ain't broke, don't fix it!

QuoteThe holes on the beam for the rod are about the diameter of the compression tube,

Is the hole on the underside also enlarged?

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Brgds
Lars

Frankentri 5.8/5.5/Inter20
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Andinista

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Posted: Mar 03, 2022 - 12:06 PM

Good to hear about the 3 bolts. When I fix the compression tube issue I’ll add some tef gel between the surfaces, now I cannot remove much tension from the v bar because of the compression tube.
Yes, the lower hole is bigger than the rod, in either case I’m not sure if enough to slide the tube out.
Dogboy

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Posted: Mar 03, 2022 - 12:18 PM

Andinista
The big problem is that the compression tube is stuck to the rod, I tried to move it by tightening the upper and lower nuts separately, with the other nut loose, without success. If I tighten both again the DS tension is about enough, I’d like some more prebend but can’t get it. Next thing I’ll try is to hammer the rod from the bottom to see if it comes out, not quite sure. I tried once but couldn’t. I’ll try starting with the upper nut tightened, to have the tube aligned with the hole. Otherwise I don’t know how I will replace the rod and tube when needed.

I experienced a similar situation with the DS compression sleeve on a Hobie 17 several years ago. If the situation is the same on your boat, then no amount of hammering on the post will free the sleeve as the threads inside the sleeve are likely packed full with corrosion.

I was able to get my DS disassembled by very carefully cutting the nuts vertically using a dremel tool with cutoff wheel. This allowed the nuts to be split in half and pulled off of the post with only very minor damage to the post itself. Then the post and compression sleeve were pulled out of the crossbar and the sleeve cut in half and pulled off of the post. The DS was then cleaned up and re-assembled with a new sleeve, nuts, flat washers, and a liberal coating of Tefgel.

sm
revintage

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Posted: Mar 03, 2022 - 12:58 PM

QuoteYes, the lower hole is bigger than the rod, in either case I’m not sure if enough to slide the tube out.

Try removing the rod from below. Make a new outer compression tube and use a similar tube as the original tube to center the outer. One problem though, you have to remove the three bolt plate and the sleeve in the beam end when sliding in the new compression tube .

But probably a total overkill. The other solution is to just add a fatter washer under the lower hole .

Edited by revintage on Mar 03, 2022 - 01:05 PM.

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Brgds
Lars

Frankentri 5.8/5.5/Inter20
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Andinista

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Posted: Mar 03, 2022 - 02:19 PM

How bad would it be to leave it like that, once I manage to separate both pieces to be able to adjust tension again? The beam would still be supported by the washers, and I can put bigger ones. I bet it’s a nightmare to put a new compression tube from the side. And then how do you release the tube from whatever you used to put it inside?

Edited by Andinista on Mar 03, 2022 - 02:26 PM.
Andinista

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Posted: Mar 03, 2022 - 02:24 PM

As it is now the beam is compressed and slightly deformed vertically, but it has been working like that for years.
Andinista

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Posted: Mar 03, 2022 - 05:05 PM

I could slide the rod +compression tube out through the upper hole, after filing the hole a bit more. I didn’t do the same on the lower hole, so I couldn’t remove it completely. I will rather cut this rod and replace it with a new set. Meanwhile I will still sail a few more days like this, it doesn’t look too bad. No way to separate the compression tube from the rod, I won’t insist because i don’t have a spare.
revintage

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Posted: Mar 03, 2022 - 05:59 PM

If the hole anyway is enlarged on the lower side, just open it a little bit more and drop the rod+tube down. If you enlarge the top hole to much I guess it will be more prone to crack, like on the ugly image I posted earlier. So bigger thicker washer on the underside will surely work.

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Brgds
Lars

Frankentri 5.8/5.5/Inter20
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P.M.

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Posted: Mar 10, 2022 - 10:19 AM

Andinista I bet it’s a nightmare to put a new compression tube from the side. And then how do you release the tube from whatever you used to put it inside?Edited by Andinista on Mar 03, 2022 - 02:26 PM.

Actually quite easy. Pack the compression tube with corrosion inhibitor, tape it to a batten, one person aligns compression tube with the hole in the beam coming in from one end, while a second person feeds the rod through the beam holes. Then simple pull the batten out and the tape will pull free. I've done it several times and is really is easy.

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Philip
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revintage

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Posted: Mar 10, 2022 - 11:21 AM

QuoteActually quite easy. Pack the compression tube with corrosion inhibitor, tape it to a batten, one person aligns compression tube with the hole in the beam coming in from one end, while a second person feeds the rod through the beam holes. Then simple pull the batten out and the tape will pull free. I've done it several times and is really is easy.

It is not the compression tube that is the problem. It is removing the reinforcement tube in the beam end!

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Brgds
Lars

Frankentri 5.8/5.5/Inter20
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P.M.

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Posted: Mar 10, 2022 - 11:29 AM

P.M.
Andinista I bet it’s a nightmare to put a new compression tube from the side. And then how do you release the tube from whatever you used to put it inside?Edited by Andinista on Mar 03, 2022 - 02:26 PM.

Actually quite easy. Pack the compression tube with corrosion inhibitor, tape it to a batten, one person aligns compression tube with the hole in the beam coming in from one end, while a second person feeds the rod through the beam holes. Then simple pull the batten out and the tape will pull free. I've done it several times and is really is easy.

revintage
QuoteActually quite easy. Pack the compression tube with corrosion inhibitor, tape it to a batten, one person aligns compression tube with the hole in the beam coming in from one end, while a second person feeds the rod through the beam holes. Then simple pull the batten out and the tape will pull free. I've done it several times and is really is easy.

It is not the compression tube that is the problem. It is removing the reinforcement tube in the beam end!

. . . as I was specifically responding (as quoted) only to Andinista's concerns to putting in a new compression tube.

Carry on . . .

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Philip
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