S.S. Bolts versus H.T. Bolts

[duke]

Hi All,

I am in the process of remaking an engine bed frame which means I have to increase the lenght of the existing high tensile bolts securing two heavy engine frame angle irons to the fibreglass upstands.

I originally had in mind to replace these bolts in stainless steel, thinking these would be stronger.
However, I am advised by my installer that high tensile steel bolts are stronger.

I would appreciate any advice or experience of this question.
The bolts in question will be 1/2 inch and will be 6" long as against previous 4" long.

One other point, I am reusing the existing angle irons pieces but have had them sand plasted and galvanised.

Regards,

Duke.

 

[tynesman]

You do not say where your boat is used,canal,river sea etc. if it is anywhere near sea water go for stainless steel bolts,yes they are more expensive but one day you will be pleased you fitted them.
Also look at lock/spring washers,all boat engines vibrate sooner or later.

Happy sailing

Tynesman

 

[tcm]

high tensile bolts are stronger, but much more susceptible to rusting in salty environment.

However, I would be very surprised if you needed the very high levels of strength of HT bolts above that availbale with SS - you aren't dangling the engine off the roof, for example.

 

[PeteMcK]

You might be... That's why you should keep an eye on the condition of your engine mounts.

 

[Guest]

hi duke,
no need to use ss. ht bolts will not react with the mild steel angle iron if you do get a splash of oggin in your bilges,ht bolts are also stronger.
good luck. chris.

 

[sonarbell]

I am sure the fibreglass upstands will give way long before your stainless or high tensile bolts ever will. Make sure the stainless bolts have 8.8 stamped on the heads and you will be fine. Just a final point, what are they screwing into? Steel or stainless inserts or is it a nut and bolt type fixing?.

 

[duke]

I should add that the boat (sailing) will be used in sea waters.

Another question : are high tensile bolts available - galvanised?

Thanks for replies so far,

Duke.

 

[steveh]

If you are fixing to galvanised steel then use galvanised bolts.
They can be obtained in Grade 8.8 which will be more than strong enough.