Cross beam holes, P18-2 :: Catamaran Sailboats at TheBeachcats.com

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Cross beam holes, P18-2

CatFan57

Rank: Mate

Registered: Mar 16, 2018

Last visit: May 10, 2023

Posts: 126
Posted: May 26, 2018 - 06:47 AM

These photos are taken from underneath the front cross beam of newly-acquired 1998 P18-2, looking up. They show two holes in the center of the beam. It looks like something used to be attached here. In the foreground of the 1st pic is the dolphin striker.

Does anyone know what these holes are for, and what was attached here?

I'm wondering if I need to get whatever it was? Or if not, should I plug the holes with silicon or something, so water doesn't splash into the cross beam?

Thanks for any help.

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1998 P18.2
Sailing out of SHBCC, NJ
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revintage

Rank: Mate

Registered: Aug 13, 2017

Last visit: Jan 26, 2025

Posts: 282
Posted: May 26, 2018 - 01:22 PM

No problems with the holes in the beam, just add two alu blind rivets. More important is to take care of the heavily corroded striker strap!

Edited by revintage on May 26, 2018 - 01:23 PM.

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Brgds
Lars

Frankentri 5.8/5.5/Inter20
Aerow trimaran foiler

https://www.facebook.com/groups/1192604934176635
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CatFan57

Rank: Mate

Registered: Mar 16, 2018

Last visit: May 10, 2023

Posts: 126
Posted: May 27, 2018 - 03:27 PM

Thanks a lot for the reply, much appreciated. However, before I plug the holes, I'd still like to understand what was/is normally mounted there, if a P18-2 owner (or anyone else) happens to see this post and can enlighten me.

If it turns out I won't be re-installing whatever it was, then I will certainly look to plug the holes - with alu blind rivets, as you suggest.

Thanks also for the warning re the striker strap. That's out of focus in the picture because (a) it's in the foreground, and (b) for some reason the photo uploaded w/ really lousy resolution. (Can't upload a better photo right now, as I'm an hour away from the boat.) So I can understand why it appears to be "heavily corroded," but actually it's not so much corroded as it has some damage in it.

I didn't ask the seller if he knew what caused the damage (probably caused by previous owner), but it appears something was allowed to rub against the strap for a while and wore some grooves in it. Looks like maybe the boat was left at anchor and the strap rocked/rubbed against a metal post or something?? I don't know, but my impression is the damage isn't sufficient to impair the strength of the strap enough to pose a problem. On the other hand, I'm not an expert, so now you've warned me and maybe I should look to have someone with more knowledge check it out to assure structural soundness.

Don't know anything about what kind of loads these dolphin strikers are subjected to when sailing, but it's something I'd like to learn more about. While I'm not new to cat sailing, I am new to ownership, and read somewhere "the dolphin striker is the heart of the structural strength of the boat" -- or something like that.

Edited by CatFan57 on May 27, 2018 - 05:01 PM.

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1998 P18.2
Sailing out of SHBCC, NJ
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revintage

Rank: Mate

Registered: Aug 13, 2017

Last visit: Jan 26, 2025

Posts: 282
Posted: May 27, 2018 - 04:45 PM

Might not be so much to worry about, I maybe exaggerated. The blurry image can have made it look worse. But there are heavy loads om the dolphin striker and front beam. If you take a closer look, also check around the strap bolts and striker rod to see if there are any cracks in the beam.

--
Brgds
Lars

Frankentri 5.8/5.5/Inter20
Aerow trimaran foiler

https://www.facebook.com/groups/1192604934176635
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CatFan57

Rank: Mate

Registered: Mar 16, 2018

Last visit: May 10, 2023

Posts: 126
Posted: May 27, 2018 - 07:38 PM

Ok thanks, I'll do that.

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1998 P18.2
Sailing out of SHBCC, NJ
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jalex

Rank: Mate

Registered: May 08, 2013

Last visit: Oct 02, 2023

Posts: 508
Posted: May 27, 2018 - 08:52 PM

Hijacking the thread, but with so much stress on dolphin strikers, how do boats like the Gcat get away with not having them? The crossbar extrusion doesn’t seem excessively heavier duty
spfx

Rank: Lubber

Registered: Nov 17, 2013

Last visit: Jul 03, 2020

Posts: 59
Posted: May 28, 2018 - 08:53 PM

I've made similar holes on my Prindle for a righting bar attachment point. My guess is the bending loads in the crossbar are greatly reduced by the dolphin striker if not virtually eliminated, otherwise you wouldn't be poking a half inch diameter hole dead center bottom in the highest stressed area of the beam.
texastuma

Rank: Mate

Registered: Nov 22, 2012

Last visit: Jan 27, 2025

Posts: 419
Posted: May 29, 2018 - 05:46 PM

Had a P-19 and have a modified 18-2. I am not sure why the holes where they are. With regards to dolphin strikers, I would heavily suggest replacing the bolts that attach the dolphin striker to the beam.

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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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gahamby

Rank: Mate

Registered: Feb 05, 2011

Last visit: Jun 15, 2021

Posts: 575
Posted: May 29, 2018 - 06:42 PM

jalexHijacking the thread, but with so much stress on dolphin strikers, how do boats like the Gcat get away with not having them? The crossbar extrusion doesn’t seem excessively heavier duty

I'm not sure about the G-Cat. SuperCat puts a sleeve inside the crossbeam with spacers that keep an even gap all the way around.

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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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