Mast step repair

[dave]

For my part you're very welcome. I'm here to help out when I can.

A good old friend of mine moved back here 15 months ago, Werner Schwarz. Some of you met him at the CCs at Holland. Werner and I built boats together back in the 70's. He and I are going to unveil my boat this spring and FINALLY get the darn thing done!
I'll take pictures of the whole process and post them here as we go. We have MUCH more to do than just the mast step!!!!!

Here's a pic of Werner's custom 30. The original builder died suddenly back in the mid 80's and Werner jumped in to finish the boat and over the years has continued to heavily modify/cut up/reconfigure the boat, so I'll have a good repair partner! I made the D4 main on his boat and the FLX13A sails on the other custom 30 behind and to weather of him.

[AJ Oliver]

More on Mast Step Repair -
Here is where "Class Struggle" stands at this point. I went in from the bottom in front of the mast step. That way I did not have to cut away any more inner skin than necessary. Starting there also enabled me to see that the supporting structure UNDER the aluminum plate had weakened. So I'll be taking out the aluminum plate and reinforcing underneath it.
I am going to replace the plywood under the step with Coosa bluewater 26, and below that, replace the aluminum plate with a stainless steel plate (to try to solve the corrosion problem caused by the stainless screw going through the aluminum plate).
Recall that the aluminum plate is canted forward, which means that tapping the screw holes in the stainless plate will be tricky (done at an angle). Fortunately, one of my ace crew dudes is also a talented machinist.
If any of you want to see photos, let me know.
Comments and suggestions welcome.
Fair Winds, AJ Oliver
# 445, Class Struggle
Sandusky Sailing Club
PS - The check for my 2010 class assoc dues is "in the mail". Even though I am not a traveling racer, I am very grateful for all the help the class offers.

[dave]

AJ, sounds like you have it going well. You may be making things too difficult on the tapping though. You can drill the holes in the deck and through the plate after the job is done and then tap them right there, everything will line up perfectly. I wouldn't even attempt to do what you're suggesting and expect things to line up, and I'm good!

When I get on my boat this spring the first thing that I'm going to do is cut an inspection hole in the forward/starboard/top edge of the DB truck. Just from looking at the fore and aft distance of the mast step and the front of the trunk, I believe that there's enough room in there to put bolts, fender washers and nylocks on the underside. Sometime in the next few weeks I'll measure on of the still together boats at the lake, but I don't think I'm wrong on this. Has anyone ever tried it?

[AJ Oliver]

Dear Dave and Others -
Thanks for all your input and advice. As you may gather, I am but no means a pro, and benefit greatly from all the "mast step" posts.
The aluminum plate is now off, and I could not believe all the powdery corrosion (oxidized aluminum?) that was both above and below it - at least a quart in total volume. That cannot be good for mast step longevity.
A loal boat pro, like Dave, also seems to think that putting in a stainless steel plate may help the corrosion problem.
Let me know if any of you want to see photos, or would like more measurements.
Thanks again for all the advice.
Fair Winds, AJ Oliver
# 445 "Class Struggle"
Sandusky Sailing Club

[dave]

AJ, glad to be of any help. The main problem is water getting in there. Without the moisture the corrosion may not even be an issue. As long as ANYTHING is used under the step that can compress even a little, the caulking bond on the bolt WILL break and then you start getting water intrusion.

Having said that, putting the aluminum plate in there to begin with was NOT a well though out plan. All boats have their pitfalls/booby traps no matter what they cost or who built them. The mast step area on the 7.9 is definitely an Achilles heel.

[Tim Bosma]

Dear 7.9er's -

For the mast step repair, we decided to replace the aluminum base plate with 3/16 inch stainless steel, and to weld studs to it that would protrude upward through solid glass layers to the mast step. The mast step will then be attached to the studs with nuts. Using this method, we will no longer have to screw bolts down through the core material into the aluminum base plate.

Hopefully, this will solve the problem of water intrusion below the mast step, as well as corrosion problems due to the aluminum/stainless interface. Let me know if you want more photos or information. (soliver@heidelberg.edu)

See attached photos.

It sure helps to have talented machinists on the crew!!!

Fair Winds, AJ Oliver # 445, "Class Struggle"
Sandusky Sailing Club

step1.JPG (86.12 KiB) Viewed 9685 times

step2.JPG (92.88 KiB) Viewed 9682 times

[wkwtucson]

I found one quarter sheets of Coosa Bluewater 26 board from Hamilton Marine 1-800 639-2715
1/2" thickness for $72.50 plus shipping.
kevin

[wkwtucson]

I have ordered some 1/2-inch Coosa Bluewater 26.
You can get quarter sheets cut from 4’x8’ sheets from Hamilton Marine shipped to your door.....
1 800 639-2715, talk to Tom.
$73 plus shipping (another $30 or so)
I will use the Coosa where ever I replace the balsa.
The plywood under the step is coming out with the old plate and getting West System Glass with Hardners (and/or Coosa drilled with ¼-inch drill holes every 3-inches and glassed)
I have purchased ¼-inch thick and 10W x 12L” 304 Stainless Steel Plate even though I know it is probably over-kill, it will fill the same void as the old plate.
I have Stainless steel bots that are ¼-inch longer than the ones that came out of the old plate and tabernacle.
I can cut them off after installation with a dremel metal cut-off wheel, but I cannot add to after installation, so longer I considered safer, ....since I am guessing at the original deck step elevation due to the step depressing and no other boat to measure against.
The bolts will be welded to the SS plate going in the deck with the threads pointing up and the tabernacle goes down over the threads with a washer and nyloc nut.

As for measurements. It would be nice to have something to shoot for.
Otherwise I go to the top of the old step and guess with the thought the slight too high is better than slightly too low.
Whatever I do, I will attach posts of wood from each side of the toe rail and equal distance back from the stem for a point of reference such that I can place a long straight board across for measurements during replacement…. Essentially a template.
We need to get some template measurements from other 7.9's for the sake of the future, as there seems to be no guidance on that.
Anyone???
Kevin

[AJ Oliver]

I think you are correct that your tabernacle is depressed - and not psychologically.
More on the mast step repair . . . (with photos)

From a member . .
"I thought the depression was part of the design as I have been around this
boat for 20-years and it was always depressed.
Last year the depression became worse and I started to see some cracking in
the gel-coat and was getting soft around the fore-guy spin block."

From me . .
My symptoms were the same as yours.
In my 7.9 the intruding water rotted the plywood below the tabernacle which caused the depression.

To me, it was faster to just take out all the rotten wood - both ply and balsa - rather than wait
a long time for it to dry.

You can probably do a better job if you have access to a vacuum bagging system, but I did not
do that - just used a small jack to hold the new balsa & epoxy up there (did it from the bottom
to save as much of that good outer skin as possible).

For the deck areas around (not under) the tabernacle like where the fore-guy spin block is/was
you might consider closed cell foam (half inch thick? 3/4ths ? I forget) instead of balsa. It does not let water in.
Something like this, maybe . . (It needs to be somewhat flexible. There are curved surfaces there.)

http://www.jamestowndistributors.com/us ... oam+Sheets

[AJ Oliver]

Two more mast step repair photos . .

[captnstumpy]

Members All: I recently brought my newly purchased 1982 S2-7.9 from the Annapolis Area to NE-PA. The former owner was or someone doing the his work was an ass. Due to a marine survey, I have some soft deck/core issues to port and aft, and forward of the step. Surprisingly the step appears OK, with one exception. I found three LAG screws and one machine screw "attaching" the step to the deck. I probably could have pulled them out with my fingers. The hard part was removing the step which was "epoxied" or 5200'd to the deck. In process of surgery to remove the entire area to the edges of the cabin top port, starboard, forward. I did the preliminary sounding, and drilled a series of 1/4" holes to test the core by sight and a common moisture meter. My first question is what I product I will use to replace the balsa, as I intend to not do this again. My next concern is as said earlier, to redo the actual step to specs.
I took photos, measurements etc., but agree that it is not as critical as I may be making it. Relative "level" fore and aft, and port/starboard should be goal but it is what it is as an amateur. My main concern is safety. My next concern is fun...as a former cruiser for twelve years on the Chesapeake in my Catalina 30, and drinking Captain Morgan on "dry land", I'm looking forward to the local racing circuit having a ball at six knots...

[AJ Oliver]

Hey Captn -

There are some good closed cell core materials around . .
Like you, I know folks who will never use balsa again.

http://www.fibreglast.com/product/guide ... -materials

Sounds like you have corrosion on the aluminum plate that the tabernacle bolts go into. With an aluminum-stainless interface plus water and your gonna get corrosion like I did. Think about replacing the aluminum plate with SS.

And yes, it is way fun to blow by much bigger boats. Makes it all worthwhile.
You'll be over six knots routinely.

[wkwtucson]

...Finished the mast step repair after 5 days of work.
I took lots of measurements and photos, if someone has an interest let me know.
I followed AJ Oliver's process more or less.
The proposed new block position as a new tang on the front of the tabernacle did not function well for the foreguy so I will probably be replacing the standup block in the original position thru the deck. ...This time with solid glass around the bolts and a stainless steel backing plate. I had been getting alot of water intrusion into the deck from this stand-up block.
kevin
hull-29