26S Repair Elongated holes in base of mast

[OnTheBayou]

The prior owner of my 26S apparently let the mast go to one side or the other as it was being raised. This elongated the hole (quite a bit) where the base of the mast bolts to the brackets on the top of the cabin.
** Can someone please measure their mast from the bottom of the mast to the center of the 3/8" hole for the bolt?
I intend to use a 1/8" marine grade aluminum to form to doubler plates for each side and bolt them on or I may make a sleeve. I will then drill the hole in the correct place based on the measure you folks provide. I don't want to weld on the mast as it is just too thin to try.

 

[beamreach]

I have a '93 model that must have had the same problem as yours and a PO made an excellent repair by drilling holes around stainless fender washers and riviting them in place over the worn holes in the base of the mast. If you go this route, be sure to spray water on your drill bit constantly as you drill to keep it cool or else the bit becomes dull in no time flat from the heat. Drill bit oil will not do the job. I learned this lesson the hard way.

 

[Justin_NSA]

I like the washer fix. And they could be drilled out and replaced if they show signs of wear.

Drill bit spin speed has a lot to do with why your bits are failing.
one of the properties of stainless is that it "work hardens" under certain conditions.
too high a work speed, too low tool pressure, among others, but these are the main ones. the combination of these two generates a very high amount of heat which hardens the material you are trying to drill. Also, try drilling pilot holes.
From a quick google search, keyword "drilling stainless steel" :
Stainless can be nasty to drill. Success is enhanced with good lubrication and keeping the drill cool. The material, depending in part on the particular stainless alloy, tends to work-harden. Turn the speed down, and put enough pressure on the drill to make it CUT, not scrape its way through. A spiral chip coming off that drill is better than making dust-sized particles.

 

[beamreach]

I have no high tech metal shop but using my table mounted drill press and the atomizer spray bottle filled with water, I sneak it from my wife's makeup counter, and the stainless clamped in place, dented with an old nail set in the place I want the hole, keeping good pressure on the bit and constantly sprayed down with the other hand, I can drill a goodly number of holes off one bit. Big holes like 1/2" also take me ever increasing size bits expanding the same hole. Didn't mention to always were eye protection.

 

[OnTheBayou]

Still need the measurement for hole in base of mast

Can someone with an intact original mast please provide me with a measurement from the base of the mast to the center of the hole for the bolt? I appreciated all the advice but without the measurement and given how much the hole is elongated I'm not quite sure where to drill the hole.
Thanks to all responding!

 

[beamreach]

Sorry for missing the meat of your question. Mine measures exactly 1 inch from the base of the mast to the center of the bolt while sitting in the holes. Please remember that my bolt holes suffered from your problem too and the PO made the repairs. With the 1 inch placement everything works fine though.

 

[OnTheBayou]

Thanks, I owe you a beer and a basket of blue crabs if you every make it down to south Louisiana! Since I have ready access to marine grade (5086) 1/8' Aluminum and a drill pipe coupler with the same diameter as the mast I think I will make a sleeve to go over the mast and bolt it on.

 

[beamreach]

Good luck and get on the water soon. If I were closer, I'd head that way tonight!

 

[OnTheBayou]

By the way if you are using stainless to patch the elongated holes in your mast be carefull if you are around salt water as the aluminum and stainless steel being different metels will set up electrolysis and slowly eat away at the aluminum. This is why I am using aluminum to make my repair.

 

[beamreach]

RE stainless against aluminum:

There's been alot discussed already here about this topic and I sure don't want to open it up again. Your gooseneck is a stainless plate fastened to your mast with stainless rivits. I moved mine up recently and saw little or no corrosion, not to say it wouldn't happen. My boat has, I believe been in alot of salt water. Just about every block, cleat and other fittings on your mast and boom are fastened with stainless. The chickenhead is stainless. That sleeve of aluminum you're putting on will be sitting on a stainless bolt. What grade aluminum is it? If it's not marine grade, I'd re-think it. Our outboards are aluminum held together with stainless. I think that setup at the base of my mast may outlive me. I've only got about forty more years.

 

[OnTheBayou]

Good point to make that did not occur to me that most attachments are indeed stainless although with limited surface areas of contact. In my case I will be using 5086 marine grade aluminum (the best you can get). I will be making a ~3" sleeve formed over a 3" steel pipe with a bit of heat. Once I have the sleeve I will bolt it on with 316 grade stainless bolts and I will use silicone to limit contact. My conern was with salt water getting in between the sleeve and mast setting up electroloysis (if I wrapped the mast in stainless) and creating major problems. I live in an area with a lot of salt and you are correct with the outboards (I have four) and they are indeed held together with stainless bolts. If you have replaced any water pumps on them where they were in salt water for any period of time the stainless bolts are a pain in the butt to remove and end up coming out with a great deal of difficulty due to the aluminum corrosion that expands into the bolt threads and tends to freeze them in place - sometimes to the point of breaking prior to coming loose. When they are tight I break out a torch and gently heat it a bit to get them out. In my case I pull the lower units at least once a year to check the water pumps and then clean the bolts and put them back.
Thanks for all your responses beamreach.