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Catalina/Capri 25/250 Sailor's Forums

Catalina 250 Specific Forum

Feedback from rigger: point load on bow tang

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kevinmac
Admiral

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USA
732 Posts

Initially Posted - 01/13/2006 : 09:11:01

I had a rigger out to my boat yesterday. One thing he pointed out is that the pin on the CDI furler shackle is 5/16ths diameter, which is correct for the shackle but too small for the 3/8ths hole in the tang on the bow. He says this will create a point load here, and that I should get a 5/16ths to 3/8ths bushing made for this spot. Usually you could blame the PO for something like this, but it came from the factory that way.

I am going to talk to the factory to see if they have any comments. Would anyone like to suggest who I should talk with there? It seems to work better calling there if you have a name...

Kevin Mackenzie
Former Association Secretary and Commodore
"Dogs Allowed"
'06 C250WK #881
and
"Jasmine"
'01 Maine Cat 30 #34

Edited by - on

Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 01/13/2006 : 10:28:58

Only a driven and hammered rivet would load the pin so that forces were transfered to the bow stem evenly. The CDI does not affect your stem fitting or forestay hardware. The pin in your turnbuckle toggle that goes through your stem fitting is not a CDI component. It came with your turnbuckle.

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Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts

Response Posted - 01/13/2006 : 12:17:35

Kevin, did the rigger suggest an option of drilling out the CDI shackle to 3/8? If the shackle has plenty of meat, I would think that would be a choice.

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kevinmac
Admiral

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USA
732 Posts

Response Posted - 01/14/2006 : 02:15:43

Frank (I think fhopper is Frank. BTW, you are typing quite well for one finger, hope your hand is better...),

Please help me, I think I am clearing missing something.

The turnbuckle came with the boat, you are right. But the furler seems to be exactly designed for that size turnbuckle. I am not sure if a larger turnbuckle would fit, i.e. if the hole in the bushing, the cup, at the black plastic cover that slides down to the cup, would be large enough to accomodate a larger turnbuckle. If they did, the t-bolt at the bottom of the turnbuckle would be one size larger, and it looks to me like a larger T-bolt and shackle would interfere with the anti-rotation strap that is attached with screws to the cup. So, to quote the rigger, the shackle is the correct size for the furler, and the pin is the correct size for the shackle, but the pin is not the correct size for the tang.

Here is a picture (from CDI manual) of what I am talking about:

Do you think I could get a bigger shackle in there? And do you think I could get a bigger T-bolt to match, without going to a larger turnbuckle?

To Arlyn: Do you think there is enough meat in that 5/16ths hole to drill it out to 3/8ths? I am nervous about making this already sortof wimpy hardware weaker, since it holds up my mast... But I am not experienced enough, as you are, to be able to tell what is "big enough".

Thanks in advance for your advice.

Oh, BTW, I talked to Lenore at Catalina, she basically blew me off with "don't worry about it, it is all over engineered". But the rigger said that eventually the tang hole would wear and elongate...

Edited by - on

Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts

Response Posted - 01/14/2006 : 04:55:29

Kevin, I'd agree with Catalina's suggestion to simply use the 5/16" pin. Drilling out the shackle could be a problem in that stress cracks get a start from an irregularity in the finish... and the drilling process could leave such in the shackle holes.

The rigger is being a purist about the pin and hole size in the stem fitting... he is technically right but here is an important point... the 250 has a light rig and its loads are clearly nothing compared to the loads on larger boats that the rigger deals with. Take a Catalina 30 for example, itself still not a very large boat but with a keel weight more than four times greater than the 250 it will grunt and groan a bit when broached... whereas the 250 shrugs a broach off like it is no big deal.

btw, you didn't mention a quick pin here but this location is one place I would NOT use a quick pin...not that the pin might not be strong enough... but rather the shackle holes on the furler could enlargen slightly with time and the small balls of the quick pin might fail to capture.

Edited by - Arlyn Stewart on 01/14/2006 05:03:28

bear
Admiral

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USA
909 Posts

Response Posted - 01/14/2006 : 07:57:39

Kevin, I have had the 5/16 pin in there for at least 5 years and maybe the original, I do look at this area when the mast is down and have seen no indication of failure or undo wear.

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Tom Potter
Master Marine Consultant

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USA
1913 Posts

Response Posted - 01/14/2006 : 10:01:37

I agree for fhopper here. I added the CDI to my boat after I bought it. There was no change of hardware made on the front stay during the install. What's there is what Catalina put there. The CDI counter rotation strap goes through the turn buckle shackle like shown in the picture KevenMac posted, but the pin and turn buckle and T bolt are all Catalina original hardware. So if there's a difference in hole size between the shackle and stem its not a CDI problem.

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kevinmac
Admiral

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USA
732 Posts

Response Posted - 01/14/2006 : 14:12:41

I agree it is not a CDI problem, I think it is a Catalina problem. But based on the advice you've given, I will not worry about it.

Thanks!

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