mast bolt hole elongated

[Reidsair]

I just bought a 1991 26s, it's my first boat of any kind. I'm concerned about the hole in the mast for bolting to the tabernacle and the bow pulpit for towing. I have several questions:
Do I have an unsafe situation with an eminent failure waiting?
What caused this, and what can I do to quit causing it?
Can it be repaired, or am I looking at a new mast?
I also see that the bolt itself is slightly bent as though the mast has been torqued. Would a new, straight, bolt solve anything?
Thank you for your insights here.
David

 

[Chief RA]

Since it is aluminum it does show considerable wear but if no cracks, it does have lots of stock left between hole and mastbase. I would not hesitate to use it based on what is shown in the photo. Do be sure to adjust your shroud lines,port,starboard,fore and aft after raising that mast. If the bolt is otherwise in good shape a slight bend in it is not a problem but if it bothers you, straighten it. Chief

 

[MrBill_FLL]

there should be a SS bottom plate for the mast, which will help that.

at this point I would get the plate and see if you need to weld up the big hole you have or the plate centers the bolt for raising it.




better pic (mast sits on that plate)



bwyachts should have it.

and it should be corrected before it gets much worse - a new mast is well over 1k.

 

[Reidsair]

the plate looks good

thank you for your suggestions, I have a little more confidence here now. MrBill, the plate looks like a great idea. I can bolt the plate securely to the mast and have the pivot and wear on the plate instead of the mast. How will I know if the hole needs to be welded? Am I looking for movement of the mast?

 

[MrBill_FLL]

I'm an hour from my boat and don't remember how its attached. but you need it.

After you get it, and attach it, and try it out, you will know if you still need to have the mast welded.

any good aluminum welder can fill the holes and then you can redrill it.


try Blue water yachts .com

 

[Reidsair]

plate is ordered

I've ordered the base plate from BWY. I'll post again after I get it installed.
Thanks,
David

 

[Knuttle]

Holes

Is the hole on the other side of the mast worn similarly or is it more round.

The reason I ask is that a hole like that could have been created when the mast was lost and nearly went over the side.

Remember the forces on the mast are in the vertical plane or compression down the mast against the deck. the hole is just there to assist in raising the mast. and keeping it in position when raised. There are no forces on the mast base in the horizontal plane. pushing the mast across the cabin top.

 

[Reidsair]

Direction of forces

The hole on the other side is mostly round. I think you're right about the direction the force was applied. I wouldn't think it would happen in normal operation. It would have to be torqued or twisted forward.
When I first raised the mast, the side stays were very loose. I was thinking that was a possible factor. That should have made the hole stretch downward. It's more likely to have happened during the raising of the mast. There is no mast raising system. If it got away from the person raising it, perhaps on more than one occasion, that could have plowed a little more aft on the bolt hole each time.
I'm thinking that the new bottom plate and deck plate I have ordered will shift those side loads to the stainless steel plate instead of the aluminum mast. This is an upgrade to what is on the X and M models. I also hope the new plate will help the mast stay straight during raising.
If I could determine exactly what caused the wear, I'd change whatever needed to be changed to stop it. I've seen that a new mast would end up well over $1k. A mast raising system would be a bargain if it saves the mast. Do you think it was during raising?
The plate is ordered. I'll have to see how it fits over the hole and how secure it is. I may need the service of a good aluminum welder. I hope I don't keep spending until I could have gotten the new mast. New is nice.

 

[Reidsair]

Is this a typical deck plate?

This is the deck plate on my '91 26S. It will have to be changed to fit the mast plate I'm ordering. Is this typical of what's on other boats? Do other boats with this deck plate have a plate on the foot of the mast? I don't mind upgrading, if it really is an upgrade.

 

[Chris & Lenore]

What causes this to happen? It's from trailering - the weight of the mast (exaggerated by bumps in the road) and the constant vibration from the wheels cause the aluminum to wear. If you have the wrong size bolt and one side of the mast is over threads, that side wears even faster.

You don't "need to do anything". I have seen this on several S models (including mine). Just ensure the mast is positioned rotationally before you tighten the forestay and it will stay put. Loads are all compression with a minuscule side load.

I would also not add the plate to the bottom of the mast that you see on earlier Macs's. The factory stopped adding those in order to reduce sideways stress on the mast step when raising the mast (when it goes off center as the baby stays stretch - early 90's S models used 3/8 line which stretches a fair bit).

Oh - be sure to cut a 2x4 to fit between the mast step and the mast when trailering. It will fit sideways in the step and you can drill a hole so it bolts in place. A V in the top and a bungee to hold the mast - will greatly reduce the force on the front bolt that is elongating that hole in your mast.

Chris

 

[MrBill_FLL]

It seems I may have led you astray.... I have the older mast plate and deck plate. but also have a middle support on the mast. (previous owner did not)

I didn't know the later boats eliminated the bottom plate.
I knew they went to the newer mast step you are showing.


I have seen other S's without the bottom plate and it had a similar hole to the OP's.

-Chris, so the mast just sits on the open extrusion? that's what you recommend?

 

[Doc_holiday]

The picture looks just like mine. I would put my efforts into other projects first.

 

[timebandit]

Looks just like mine except mine is backwards.

 

[redhead78]

plate

take a small piece of aluminum plate, say 4"x4" x 1/4" to 3/8" thick, drill a hole slightly larger than bolt so it slides thru, then line it up and rivit it to the mast over the old hole area .If u have to shape it slightly to fit mast profile. Red

 

[Reidsair]

Trailering, that's the ticket!

Chris, I think you hit the nail on the head. Looking at the mast at the bow pulpit, I can flex the mast and see where the bolt would pull right into the worn place. And the bolt is threaded so that the threads are against the hole, sawing and gnawing. I'll put a crutch in the deck step plate and put a stop to that. I like the one that Copernicus is sporting there.
Thank you Red for the solution to the aluminum welders fee. I think the plate will have to be on the inside of the mast in order to continue fitting in the deck plate and the pulpit mount. Shaping may be critical, but counter-sunk flush rivets won't interfere. If I can't get it to fit well enough, the welder can fill my rivet holes while he's at it.

 

[timebandit]

I do not think there is enuff room to install plates between the mast and the step sides.

 

[MrBill_FLL]

So everyone else has the bolt going thru the mast but me?

which means everyone's mast is 3" closer to the bow than mine too....

 

[Reidsair]

nearer the bow to thee

the bolt through the mast runs through the slotted holes in the deck plate, further aft.
It looks like we would be in the same place.

 

[finding41]

I just bought a 1991 26s, it's my first boat of any kind. I'm concerned about the hole in the mast for bolting to the tabernacle and the bow pulpit for towing. I have several questions:
Do I have an unsafe situation with an eminent failure waiting?
What caused this, and what can I do to quit causing it?
Can it be repaired, or am I looking at a new mast?
I also see that the bolt itself is slightly bent as though the mast has been torqued. Would a new, straight, bolt solve anything?
Thank you for your insights here.
David

First. Welcome to the forum!
I think the rigging wasn't set properly for some time... But it could have happened witht the mast down. I had my mast and the wood piece that it rests on jump out of the holders in the cockpit and lean hard to one side. ( I saw this happening while I was towing it on the 401 @ 100km/h!)
I stopped and put it back in place... But if someone didn't notice and kept driving like that....
I think I know what the holes in the two SS pieces that the wood mast support go in are for.... Screws! That's what I use now.
-To repair you could take it some place that welds aluminium and have them patch it. (I'd do both sides.)
-Probably best to get a new bolt.
Good luck! Enjoy the boat!

 

[Chris & Lenore]

I mentioned earlier that you don't really need to do anything to the elongated holes. It can't move (even with the holes even worn to twice their size) because of the pressure the rigging exerts - and - the way the bolt heads in the mast step "trap" the mast.

On Teliki, these bolts heads prevent the mast from rotating or moving fore/aft my more than about 1/4 inch. Once the rigging is tensioned it doesn't move at all. Have sailed five years with worn mast holes and never had any movement...

I would never bother trying to "fix" anything. if I was going to invest in this area, I would add a bottom plate and spreaders that allow mast rotation.

Chris