Keel bolt backing plate rust

[Lucent83]

I'm looking to buy my first boat. I viewed a 1990s Sadler 32 today, and there's lots to like, but the broker made me aware of some corrosion on the keel bolt backing plates.

The keel was replaced when the boat was a couple of years old from a lifting keel to a fin keel to improve performance. This was 30 years ago with no problems reported since.

I'm a bit out of my depth with how serious the problem might be, and would appreciate your thoughts.

 

[rogerthebodger]

I had a similar issue with some chain plates on my previous boat.

I simply removed on st a time and replaced then with new steel plates

 

[Tranona]

Not unusual. They are mild steel and obviously rust over time. Unlikely to be any problems with the bolts themselves. Normal treatment is to remove the nuts (one at a time) clean up the rust and if there is no serious corrosion, treat and paint. If too corroded replace, probably with 316 stainless.

 

[V1701]

Not all brokers would have done that! Rust always looks worse than it is but I'd have a dig around with a screwdriver or something to have more of a clue about the extent of the corrosion & whether the plates might need replacing. I don't think a surveyor (if you plan to have one) would even lift the floorboards to look at the keel bolts...

 

[Lucent83]

Thanks all. That all sounds promising. With it being a first boat I'm erring on the cautious side!

 

[Tranona]

I don't think a surveyor (if you plan to have one) would even lift the floorboards to look at the keel bolts...

Yes he would. It is a standard item on the check list.

 

[010169]

Google phosphoric acid for rust treatment if you go the well advised route of treating the plates. I have used it very successfully to cure rust.

 

[Baggywrinkle]

Personally, and this is just my personal opinion, I'd walk away and keep looking.

My reasoning is that the previous owner(s) look to have neglected the bolts they couldn't easily reach ... and made a half-hearted job to tart up the others at some point in the past, and it looks like a couple have recently been disturbed - why? What is the rest of the boat like? Definitely get a survey and in the meantime here is some advice from PBO ...

How to check keel bolts - Practical Boat Owner

 

[Rappey]

There was a thread some time back with the same problem but theirs looked a whole lot worse. The nuts looked like they had had it.
Once they chipped off the rust it was amazing how good the metal actually was and it looked more than acceptable once painted

 

[vyv_cox]

The original studs and nuts would have been stainless steel, probably 316 and 304, but it appears that they are now carbon steel. Not a big problem, Moody and Beneteau use carbon steel but they need to be kept in good condition. These look poor, so at least one nut needs to come off to assess.

 

[Lucent83]

The original studs and nuts would have been stainless steel, probably 316 and 304, but it appears that they are now carbon steel. Not a big problem, Moody and Beneteau use carbon steel but they need to be kept in good condition. These look poor, so at least one nut needs to come off to assess.

Thanks for the advice. The boat is in the water at the moment, haul out not available until Feb. Is removing a single bolt, preferably the forward one likely to be possible/sensible?

 

[Tranona]

It is actually a stud with a nut. No issue with removing the nut. There does not seem to be any sign of leaking and the rust is from water in the bilge and with a nut removed you can assess the state of the stud and the backing plate. The stud will almost certainly be fine and it will only be the plate and nut that need attention or replacement. However it may be wise to wait for your surveyor as unlikely the current owner will give permission to remove a nut, but may if the surveyor things it wise.

If the rest of the boat looks OK then an offer subject to survey is the next stage. It is then normal to have some form of renegotiation if the survey identifies issues like this.

 

[PeterWright]

Hi Lucent 83,

There may well be a lroblem with removing the nut. If you put a socket on the nut with a breaker bar and heave, the chances are fairly equal between the nut unscrewing from the stud (what you want) and the stud unscrewing from its tapped hole in the keel (not what you want). For this reason, shipwrights will often split the nut off the stud rather than risk disturbing the bond between the stud and the keel jointing material.

Before starting any job on your keel fastenings, its worth cleaning as much rust off anything in the bilge then ensuring the bilge is clean and dry. Howeever careful you are, you may end up drawing a stud in which case, the last thing you want is water, dirt or rust flakes falling into the tapped hole in the cast iron keel. Keep a hoover handy while you work and keep the bilge clean.

Peter.