Fitting mast step plate

[yankeefan]

Hi Guys - I need some advice on what to do here. I'm fitting a new mast step plate and the bolt holes for the old flange don't match up with my new RigRite hinged mast step assembly flang; the old one had a larger profile.
My solution is to trim off the bottom of the mast above the old hardware holes and drill/tap for new screws. Can anyone in the group provide some guidance or talk me out of this approach? Something in my gut is telling me to beware taking a saw to the mast.
Below are a few pictures of the issue.

[tjr818]

Are you switching to a hinged mast step from a fixed step? If so you would probably need to cut a bit off the bottom of the mast in order to have the correct total mast height. If the mast is too tall none of your standing rigging will work. You want the total length from the mast head to the deck to remain unchanged.

[yankeefan]

Thanks for the insight. The overall height difference is a concern, but I believe the rigging can be adjusted without any major upfit changes. The old hinged step assembly is pictured. I tried for months to locate the manufacturer of the original, but came up empty handed. In an earlier post, there was another owner who has the same piece of hardware but we unable to determine if it's original to the boat. My CD25 was built in 1975. The RigRite assembly is made specifically for this model and application, so I have confidence it will be a good fit once completed.
If there wasn't excessive corrosion around the old screw holes, I would have considered having the holes filled but trimming the bottom of the mast seems to be the best option but I hope someone in the group can confirm I'm not making a huge mistake.

[John Stone]

So the issue is the old hole is too high for the new base plate. And the new base plate has a riser which is what is causing the old hole to be too high. Is that correct?

Doesn’t look like the old though bolt hole can be avoided.

Without better pictures and an accurate drawing depicting what I’m am looking at my best assessment is you need to cut the same amount off the bottom of the mast that corresponds to the riser in the new base plate which “should” bring the hole into alignment so you can drill through the new base plate leaving enough material above the hole to secure the bolt.

If all that’s correct and you need to cut the a small amount off the base there are two ways to do it that come to mind.

1. Draw a very accurate line around the base of the mast where you need to cut. Then cut shy of it and use a grinder to then carefully grind down to the line.

2. My preferred way is to lay the mast on some block or a stand the same height as the base of a chop saw cutting deck. Square everything up dead flat. Use a metal cut-off wheel made for your chop saw to cut off the base of the mast. Quick. Simple. Dead flat and square. Cut off wheel for a 10” or 12” shop saw are less than $10.

Whatever method you use the base of the mast needs to be cut square. File off any burrs. Use the best tools you can to help you do the job right. When you drill the hole drill from each side. Don’t try to drill all the way through from one side to the other.

The corrosion around the hole is galvanic corrosion. The best way to prevent that is to use some UHMW tape to help isolate the washer from the spar. Then use Tef-Gel or similar product on the boat to keep it from making contact with the aluminum mast.

All the above is based on the notion I am understanding the issue. Can’t stress enough for you to make an accurate drawing so we can understand exactly what we are looking at.

[Steve Laume]

I would determine the difference in height between the two set ups and cut that amount off of the base of the mast. I would be tempted to take off a tiny bit more if it would eliminate that old corroded hole. This doesn't seem to be rocket science. Once you have a fresh base on the mast, you can mark a new hole, where you want it and be good to go.

I have cut quite a bit of aluminum. Deck rails, for homes, spinnaker poles, masts and boom sections. I always use a miter saw. It is the best way to get a straight clean cut. Do not use a metal cut off wheel for aluminum. They are designed to cut steel and cast iron. If you try to cut aluminum with one, it will clog, generate a tremendous amount of heat and not do a good job if you even able to finish the cut. A standard carbide blade works very well for aluminum. It will give you a nice clean cut. You just need to task a file and run it around the edge to remove any burr. Make sure to wear eye protection but other than that it is very easy to cut.

I am not sure if it is the right thing to do but I always grease inside of the first few inches of the mast before I step it, Steve.

[John Stone]

I have cut quite a bit of aluminum. Deck rails, for homes, spinnaker poles, masts and boom sections. I always use a miter saw. It is the best way to get a straight clean cut. Do not use a metal cut off wheel for aluminum. They are designed to cut steel and cast iron. If you try to cut aluminum with one, it will clog, generate a tremendous amount of heat and not do a good job if you even able to finish the cut. A standard carbide blade works very well for aluminum.

I have not cut as much aluminum as Steve has. But, I have never had the trouble cutting aluminum. I use 12” abrasive disk made for non ferrous metal. It has the correct arbor for my saw. I have used these disks on 1/4” silicon bronze, 3/16” Naval brass, and aluminum spinnaker poles. Never had a bit of trouble. They do make special toothed blades for cutting metal. But they are expensive. I might have one if I cut lots of metal. I wouldn’t use one of my toothed wood cutting blades on aluminum like I see people do as it ruins the blade. And if you use an old dull one you are asking for trouble.

Steve raises a good point about the corroded hole. Though it would not be my first choice you could cut the mast down. You may need need new standing rigging. Also it will change the height of the boom above the deck. Could also cause problems with jib luff length depending on how close it is. But if none of those items are a problem it would be a simple solution. However, if cutting the mast down causes problems you don’t want to deal with there are other options. If the bolt goes through the base plate then there is probably not much load on the mast side wall. Looks like your vang bolts through the hole. If the load is mostly on the base vice mast you might be able to fill with epoxy and redrill. The better solution would be to get a metal grommet spacer from a place like McMaster Carr. Then, grind out the hole with a dremel maintaining a chamfer profile, fill with with thickened epoxy (use a flush backer on the inside to prevent the epoxy from extending past the interior mast wall, then drill for the grommet. A welder experienced with aluminum could also repair it I think though I don’t have expertise with welding.

[Steve Laume]

I didn't know there were abrasive blades for non ferrous metals. So I learned something new. Thank you, John. If I had read your post, I would have slapped a metal cutting blade on my saw and it would have been a standard metal wheel. Thank you for clarifying that it needs to be a non ferrous wheel. I will probably continue to use a carbide blade as I have some cheaper ones I don't care much about and it doesn't seem to dull them all that much.

No matter what blade you choose this should be a pretty simple task, Steve.

[John Stone]

I didn't know there were abrasive blades for non ferrous metals. So I learned something new. Thank you, John. If I had read your post, I would have slapped a metal cutting blade on my saw and it would have been a standard metal wheel. Thank you for clarifying that it needs to be a non ferrous wheel. I will probably continue to use a carbide blade as I have some cheaper ones I don't care much about and it doesn't seem to dull them all that much.

No matter what blade you choose this should be a pretty simple task, Steve.

Steve, Yes. There are abrasive blades for cutting non ferrous metal. It’s worked fine for me. But, since your post I have been reading up on other techniques for cutting aluminum and other nonferrous metals. Sounds like using a regular toothed blade is not only fine but may be preferred for some applications. I’m leaning new things too.

The challenge with forums is one often gets a short answer to a complicated question. While there is often great advice on the forum, IMO it is not a substitute for folks to dig deep into vetted sources of info on their own and make sure they are doing their home work. Typically my answers tend to be long because that’s the kind of info I would like to get. But sometimes, typing out details on a phone is challenging.

I spend a lot of time researching any new task I am taking on. I read, I take notes, I contact people I trust. I gather the best info I can before I made finalize my plan. I suspect you do the same.

Anyway, I may improve the way I approach cutting metal. I have a friend with a metal cutting band saw. Slow turning. Safe. Blade never seems to get hot. But, I’ve never been able to justify the cost or the room to store such a machine. So perhaps a different blade for my chop saw as an experiment....

I always learn something from your posts. Keep them coming.

[s2sailorlis]

did you check with Dwyer to see if they had something too?

The new mast step, and mast, look exactly like my CD22 setup.

[yankeefan]

Thanks to everyone for the informative comments and suggestions. I was able to determine where to cut by taking a measurement of the overall length of the mast with the old step plate attached and a measurement of the new step plate and subtracting the difference. I took 3 separate measurements using rigging/hardware attachment points on the mast as reference points for the length. I purchased a very nice but inexpensive carbide tip blade for non-ferrous metals from Amazon for under $30. Now all there is to do is get the boat back the garage and make the cut. I will post a follow up for anyone interested. I appreciate you all lending the knowledge base.

If anyone has any pictures of their RigRite hinged mast step plate installed, I would appreciate any pictures or follow up posts as I am still undecided if the through-bolt attachment on the old hardware is appropriate of it the new plate should be drilled, tapped and machine screw attached. The only reference for installing this so far is a mention of a 5 bolt attachment, which I assume because of the casting it would be drilled and tapped.

[robwm]

My personal preference is to not cut anything off unless it is absolutely necessary: hard to put it back together if it doesn't really work, and, unknown unknowns tend to appear whenever you change dimensions/lengths on rigging.

Relative to your situation I don't think that the corrosion that you are seeing at the bolt hole is actually that critical in terms of the structural integrity of the mast. The through bolt is not intended to prevent the mast from tipping (the shrouds do that). Rather, and the way I see it, the purposes of the bolt going through the mast and collar are to: prevent the mast from shifting around its base (the collar) or somehow jumping out of the inside collar, prevent the mast from slipping off one lip of the collar as the hinged plate rotates on its hinge as you lower the mast and deforming/bending the opposite lip, and, providing a point of attachment for blocks (if used that way, not clear from your pictures if that is the case).

I would be tempted to first try using a suitably sized washer or tang to bridge over the existing enlarged bolthole and using a slightly longer bolt to account for added thickness. This then assumes that the collar would have to be drilled near its top (as you've shown) to accommodate the through bolt. I realize that is not straight forward but you may be able to find a machine shop to do it for you. As a back up, you could also add a couple of screws on each side of the mast near the through bolt location. This would require drilling and tapping to accommodate the screws. These would then take over/duplicate the function of the through bolt.

I have the same hinged plate and collar that you are looking at installing on my CD22. Attached are photos of the mast and hinged step. They were installed by the PO so I don't have photos of the hing in use (as the mast is lowered down). However they may be of use to you for visualizing the arrangement "in-situ".

[Steve Laume]

Cutting the same amount off of the mast as the difference in thickness of the mast plates will insure that the rig dimensions stay the same. It will also give a nice un-corroded surface to sit on the base.

I would not drill and tap any fasteners to hold the mast in place. That is a wet area and you will be dealing with dissimilar metals. The threads are sure to seize and create problems some where down the line.

Raven has a bail that is through bolted for the vang. One thing I added was some nylon washers between the vang and the mast extrusion. These allow it to swing freely and keeps the stainless vang from coming in contact with the aluminum mast.

In the last pictures, there is a lock washer under the elastic stop nut. This is certainly redundant if not just wrong. It is not doing anything and should be replaced with a flat washer, Steve.

[robwm]

Good observation on the split washer Steve. As I indicated in the post, the PO installed the hinge plate including the through bolt and split washer. I agree that the split washer is redundant with the use of a lock-nut and plan to remove it at some point after I finish more pressing items that need fixing.

I agree with your concern about potential seizing of screws installed as an alternative solution to cutting off of the mast. However, these would not be located in a constantly saturated situation, if at all, and I think that this can be managed with the use of Tef Gel or similar anti-seize. An additional and easy preventative step for this would be to back off and re-apply anti-seize to the screws every couple years or so as part of regular maintenance.

I guess lacking your extensive experience working with metals, my preference is to avoid surgery that cannot be reversed unless no other options exist. Learning a lot from this thread.

Robert

[John Stone]

Cutting the same amount off of the mast as the difference in thickness of the mast plates will insure that the rig dimensions stay the same. It will also give a nice un-corroded surface to sit on the base.

I would not drill and tap any fasteners to hold the mast in place. That is a wet area and you will be dealing with dissimilar metals. The threads are sure to seize and create problems some where down the line.

Raven has a bail that is through bolted for the vang. One thing I added was some nylon washers between the vang and the mast extrusion. These allow it to swing freely and keeps the stainless vang from coming in contact with the aluminum mast.

In the last pictures, there is a lock washer under the elastic stop nut. This is certainly redundant if not just wrong. It is not doing anything and should be replaced with a flat washer, Steve.

Concur with all Steve’s comments. Don’t put SS and aluminum together if you can avoid it. Nothing good will come from it. There will be plenty of saltwater bathing that bolt. The moisture alone at sea level has plenty of salt in it. Takes one minute or less to remove that washer. Use a nylon one or you can make your own from black UHMW.

Once you mod the boat with a new heel step it is correct to mod the mast to accommodate it. Trying to keep parts together or a retain a design after you make changes can lead to inefficiencies or structural issues. Not always of course...so use your judgment.

[yankeefan]

Thanks to the CDSOA community for all your posts and experiences. After a lot of consideration and measuring and re-measuring, I made the cut and installed the new step. I did take the advice given and measured the total length of the mast with the old plate installed and measured the mast with the new plate dry fitted and subtracted the difference. I took measurements from multiple fixed reference points (cleats, block mountings, and the winch) so I got a hyper accurate reference from which to cut all-way round. I purchased an 80 tooth 10" TGC Aluminum and Non-ferrous metal saw blade for my chop saw and then spent about an hour leveling and squaring the rig to the blade. I had to cut multiple custom shims and leveling blocks and utilized just about every clamp in my inventory, but finally cleared the internal wiring, held my breath and mad the cut. I must say the blade was worth the $25 as it went right through with no issues; perfect, clean cut. If you're wondering, I cut a light 19 mm off just in case some grinding was necessary as it was difficult to tell if the cast aluminum step mounting surface was completely square. Unfortunately, I was so consumed by making sure the mast was level and square to the blade, I failed to document these steps with pics to share. I did take a few at the end when I drilled and tapped the holes. I called Rig-rite and they recommended 5 bolts, which I thought was excessive, so I went with the 4-bolt pattern you see in the pics. I really think the through bolt that was on the original installation would be sufficient, but with the remnant of the old hole still present, I thought better than to drill out above it, opting to bore virgin metal with no corrosion behind it. Pro tip: because of the dissimilar metals (aluminum contact with the stainless hardware, I used anti-seize lubricant on the inside contact points as well as under the washers for the bolts. I also used thread locker on the bolts to make sure they don't loosen with the temperature swings and while trailering. We used this technique at the truck plant, so I hope it translates to this marine application with no regrets. Anything to inhibit further corrosion is worth a shot on a 45-year-old mast.
The problem with a project like this is scope creep. In addition to installing the new step and base plate, I also took the sails in to be washed and refurbished and replaced the sheets. I installed all new running rigging, ran all new electrical and VHF cable, new anchor light, new steaming/deck light, and replaced the old wind Windex which I broke when stepping the mast.
If you made it this far in this post, congratulations and thanks again for all the comments. The insight of other owners and past experiences is why I renew my membership each year.