What Kind of bolts are used to mount Outboard's ?

[JJB]

I am replacing my force ob with a Johnson and wanted to know what type of Bolts to use on it . The ones I have taken out seem to be very light like aluminun and not ss . What is the right bolt to use ? and is marien -tex ok to fill old holes with ? Thanks JJB

 

[Texasmark]

Re: What Kind of bolts are used to mount Outboard's ?

I am in fresh water. I would get the largest grade 5 (3 strike marks) or grade 8 (6 strike marks) NF thread (that will fit in the holes) with flat washers for both sides and self locking nuts, in cad plated steel.

Or, if you prefer, or are in salt water, I would go to SS. You would probably have to go to a marine supply store or dealer to get them.

The bolt would be 1/2" dia or thereabouts and the tensile strength (resistance to pulling apart) is like 50,000# per sq inch for the grade 5 and higher for the grade 8 so you aren't going to pull the bolt apart. Bolts aren't usually made from aluminum (probably due to ease of galling and work function)....maybe titanium but that to me is way overkill for price to functionality in this type of application.

Mark

 

[Chris1956]

Re: What Kind of bolts are used to mount Outboard's ?

JJB, We normally use the largest bolt that will fit in the mounting holes (usually 3/8"). I recommend stainless, with SS flat washers and SS locking nuts. SS is plenty strong for this purpose. Put some caulk on the bolts to seal them.

 

[JJB]

Re: What Kind of bolts are used to mount Outboard's ?

Hey thanks guy's for the info ! My old holes dont line up and will need to drill new ones . Can I use marine -tex to fill the old holes below the water line ? Thank's JJB

 

[wilde1j]

Re: What Kind of bolts are used to mount Outboard's ?

That will work ... make sure water can't get to the wood core. And use nothing but the largest SS bolts that will fit the motor bracket ... never use cs bolts or nuts unless you're fond of rust stains and bolt failure.