SailNet Community - Reply to Topic
Thread: BOLT head in the Bilge... Reply to Thread
Send Trackbacks to (Separate multiple URLs with spaces) :
Post Icons
You may choose an icon for your message from the following list:

Register Now

In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

  Additional Options
Miscellaneous Options

Click here to view the posting rules you are bound to when clicking the
'Submit Reply' button below

  Topic Review (Newest First)
02-22-2013 05:22 PM
Re: BOLT head in the Bilge...

It is nice to read about an easy fix for once...LOL
02-22-2013 07:10 AM
Re: BOLT head in the Bilge...

Read the entire escapade in one shot, so was glad to hear the positive outcome.

However, I second the concern that you use the correct bolt and not just what you found in your stock.
02-21-2013 10:13 AM
Re: BOLT head in the Bilge...

02-21-2013 09:40 AM
Re: BOLT head in the Bilge...


Congrats on the success!

Just a thought: If your replacement bolt is identical to the one that snapped, then keep a close eye on it. From your description it seems to differ from the others, and it sounds like it may not be up to the task for long. You might want to consider finding a bolt that's identical to the one that didn't break.

02-21-2013 09:15 AM
Re: BOLT head in the Bilge...

Good Job lesson learned. Broken bolt heads are almost always from loose bolts & vibration. Make sure you check your alignment & repair vibration issues
02-20-2013 03:44 PM
Re: BOLT head in the Bilge...

Sounds like the correct bolt got lost and something that was at hand got substituted.

Congrats and now head out and buy a lottery ticket.
02-20-2013 11:53 AM
Re: BOLT head in the Bilge...

THANKS EVERYONE... Sure got a ton of replies and advice, and I appreciate all of it! Here's what I did...
Lined up the local boat yard to do the work if what I was going to try failed. Then, walked to Home Depot. Bought a bottle jack, a breaker arm (long socket wrench), PB Blaster Penetrating, and a big Visegrip (I only had the medium size). Last night I PB Blasted the bolts. This morning I put the jack in the bilge under the stern end of the engine, jacked it tight, but not enough to move it. Then with my fingers crossed I put the big wrench on the remaining upper bolt and slowly cranked. Woohoo, it moved. I removed it. That was probably a 5 inch bolt with threads only at the end (odd since the broken head had threads right to the head). Next I removed the bracket by taking off the upper nuts on the mount. Then I got the big Visegrips and put it on the end of the now revealed broken bolt. It moved so easily I thought the wrench had come off. I removed it with my fingers. It was only about 1.5" long and all threads. So the two bolts were different. I thought I would be visiting a hardware store or the boat yard for a new bolt, but a quick look in my stock and I saw I had three SS bolts that were identical to the broken one. I used a lock washer and one of those bolts to reassemble.
I suspect that the bad bolt was very tight, and then when the opposite corner was raised during the alignment it stressed the neck of that bolt and it eventually gave way. I'm just glad I found it.
Thanks again!
02-20-2013 11:51 AM
Re: BOLT head in the Bilge...

Originally Posted by SloopJonB View Post
I'm betting the shaft of that bolt is stuck really tight. I've found over the years that the single biggest reason for bolt heads failing is over tightening - someone leaned on the wrench until they felt the bolt head start to give and called it good enough.
Yes... overtightening a bolt can compromise the strength of the bolt but this is unlikely as Grade 8 bolts have a tensile strength of 150,000 psi... that's quite a bit for hand tightening... but if the bolt was over torqued I could see it failing... I believe it was more due to an overload condition on the engine causing the over torqued bolt head to break off... which is why you must change not only the two bolts shown on the photo but all bolts holding this engine... bolts are cheap... ruining your alignment is more costly... The preload, or thread tension in a fastener is higher when the type of steel being used is grade 8 in quality which if you can get aircraft bolts that would be the best overall grade.
02-20-2013 11:16 AM
Re: BOLT head in the Bilge...

I'm betting the shaft of that bolt is stuck really tight. I've found over the years that the single biggest reason for bolt heads failing is over tightening - someone leaned on the wrench until they felt the bolt head start to give and called it good enough.
02-20-2013 08:02 AM
Re: BOLT head in the Bilge...

Sometimes simple is better. If you have a bit sticking through dremel a slot or an 'X' and take it out with a screw driver (of course penetrating oil etc.. first)

As others have said, I'd replace all of the bolts, but first I'd call the service who did the realignment and tell them they have some explaining to do, followed by a refund or repair. This didn't happen because they did the job right, not in a couple of months.
This thread has more than 10 replies. Click here to review the whole thread.

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

For the best viewing experience please update your browser to Google Chrome