please help ID this bolt

[gregski]

I found this bolt rolling around in the bottom of the hull. It is approximately 3/8" (just a little smaller, 0.360") and I forgot to measure length but by photoshop measuring it's around 2.25"-2.5". Any thoughts on what it is for? My best guess is that it is the connecting bolt at the rudder. If that's the case, it was replaced by the previous owner. If it's for something else, I haven't figured out what's broken.
22855

[wolfeman131]

kaneboats may be better able to confirm, but looks like a coupler bolt to me.

http://www.skidim.com/BOLT-SET-SHAFT-COUPLING/productinfo/CPBLT3816X12/

http://www.skidim.com/searchprods.asp

[mjr119]

I dont think that is a coupler bolt. Looks like it has an unthreaded portion under the head. Hard to see on my phone.

[BamaMojo]

kaneboats may be better able to confirm, but looks like a coupler bolt to me.

http://www.skidim.com/BOLT-SET-SHAFT-COUPLING/productinfo/CPBLT3816X12/

http://www.skidim.com/searchprods.asp

Yep, looks like coupling flange bolt. They work loose. Just had mine tightened.


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[gregski]

I dont think that is a coupler bolt. Looks like it has an unthreaded portion under the head. Hard to see on my phone.
Yes, about half the length is unthreaded. It sheared at the start of the threads and the first threads there are worn down a bit.

[DOCDRS]

yep , id say couple bolt

[kaneboats]

Easy enough to check. Reach around in there and make sure there are 4 bolts. The nylock nut is kind of a giveaway that it's out of the coupler. Wonder if they came loose and one broke off. May have been replaced previously.

[Fastest1]

Plenty of mention of them being loose when checked.

[smorris7]

Checked mine and ALL 4 were loose. I had changed props thinking I had dinged it because there was a small vibration but vibration could have come from all the bolts being loose.

[sivs1]

So not to sound like a total newb, where are these 4 bolts that apparently I need t check?

Rudder? Drive Shaft?

[smorris7]

The coupler on the drive shaft.

[gregski]

Just to follow up, this was in fact a coupler bolt.

When I checked last year, all four were in place which tells me that this had happened to previous owner and had been repaired. The kicker is that this weekend, our drive shaft completely separated and I found 2 more sheared bolt in the bilge. I know that all 4 were in place last season but I haven't checked since then so I can't say when the others may have failed. It failed at a rather odd time: we had finished a surf session, drained the ballast and we're "puttering" into a cove at low speed when suddenly we lost power and definitely didn't have a prop strike of any kind (we were in over 100 feet of known clear water). I would have expected failure when you first start, for example. What likely happened is that they had previously worked loose just enough to allow some lash/vibration/etc which would accelerate this failure. So, this has moved way up on my list of periodic checks. What are your experiences? How often are you checking? Always loose and need tightening? This seems a bit excessive...

[DOCDRS]

These have nylock nuts on them. Once they have been loosened and tightened a few times they should be replaced. They should be checked yearly when doing your alignment check. So tyey should be replaced every 3-4 years imo. I know not everyone checks their alignment yearly but the nuts should be .

[kaneboats]

At least once per year and again after any strike event or before any big weekend or trip.