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tim79mc 05-28-2012 10:35 PM

1979 Skier floor replacement leads to stringers and more
Hi all,

I first wanted to thank everyone for posting such great posts on restorations of older Mastercrafts. I have learned enough to have the confidence to start work on my own boat.

Last year, during a power turn the driver's seat ripped out of the floor. Didn't take long to figure out that the floor was rotting out. So, over the winter I did my homework and started ripping the floor out this spring.

The floor was mush under both the driver's seat / footbox and observers feet. Everywhere else, it was ok - thought I might have an easy job. After pulling the floor, it was clear the bow end of each stringer was rotted. So, these probably need to be repaired also...

When I took the bulkhead out (where the driver's feet would rest), there was an awful smell, like something rotting. I had noticed whiffs of this, but could never figure out where it was coming from. Despite being dry all winter, water was leaking out of the bow foam. I poked and prodded and found that the foam was water logged on the bottom.

I'm in deep now, and no turning back. I love this boat and will have to rely on pulls from friends while I get "Old Blue" back in the water.

I hope to share my path and learn some lessons from the experienced folks on this site.

I'm posting pics of my progress on

nascar 05-29-2012 04:42 AM

great work and super pictures !

tim79mc 06-03-2012 12:48 AM

I had a great day today working on the boat. Pretty much a full day effort with lots accomplished. Here goes with where I'm at, one post at a time.

The ski pylon is the biggest problem I have right now. It seems to be frozen (corroded) into the bottom mount. At floor level, the pylon has corroded horribly. Based on an initial assessment of the depth of corrosion, I want to replace this.

I've soaked the bottom mount with liquid wrench, but no give. I've hit the cross member with a dead-blow sledge, but nothing loosens, though the stringers are limiting how much it can rotate. Based on another thread, I'm expecting I will have to cut the pylon and drill out the bottom.

Here's the top corrosion:

The bolts holding the cross brace into the stringers were not doing much...

Any ideas for where I can get a replacement pylon? Or even better, some magic on how I can fix my current pylon? I love the classic look of this pylon and hate to see it go.

Old school pylon

tim79mc 06-03-2012 01:04 AM

Foam removal, part 1.

I started by pulling out the bulkhead - at this point, I was not planning on getting rid of the foam. However, there was a nasty smell that had started last summer coming from the front and I would soon find out where it was coming from.

The bottom of the bulkhead was rotted and was mushy over on the driver's side.

Outside of the primary stringers, there are fiberglass forms that look like they help form the foam during manufacturing. They also hold water really well as there are no drainage holes. This pic is from the driver's side - would be just in front of where your left foot pushes on the bulkhead.

This is the foam that came out of it.

About halfway through the foam removal - probably about four hours' effort, though I was learning a lot about what saws to use, what position works well. My carpenter's saw and sheetrock saw where the best tools. A 2" putty knife was perfect for cleaning up the foam near the hull.

Whitening of the fiberglass under some of the foam. There's a lot more of this under the rest of the foam - pictures of that tomorrow.

I was frustrated by how the foam would wiggle around the edges, but I could not just pull it out. Turns out there's a 2x2 in the front portion of the bow that holds all of the foam in.

tim79mc 06-03-2012 09:42 PM

Here are pics of the bow area with the floatation foam removed. From what I've read on the web, the hull has some pretty good hydrolysis going on in the areas of white. At the very front of the bow, there was a piece of foam that came out carrying some of the fibers from the hull. Everything seems solid - no delamination voids that I could tell by tapping on the hull.

Any advice on what needs to be done? I am thinking about grinding down the white areas and laying up a few layers of fiberglass to replace the material.

Also, I would like to add foam that does not contact the hull - the only places in the hull where there is whitening of the layup is under the foam. Does the foam provide any structural function? If so, do I need to pour 2-part foam at least in the below floor area. After all of this work, there is going to be storage up front!

At the front of the bow, you can see a 2x2 cross brace (is this used to pull the hull from the mold?). The foam came out as one big chunk once I got enough out to free it from this brace. The darker coloration in the bow is from water that got into the boat from a quick rain shower. It's white when dry.

Front bow foam containing fibers from the hull

tim79mc 06-03-2012 09:55 PM

Engine is out
I was not planning on removing the engine when I started work on the floor. This added several days of research, planning and buying more stuff to get this to work. I wanted to rent a steel gantry crane, but couldn't find one locally. I'm not a metal guy, so I found plans for a wood one, did the stress caclulations (I'm an engineer by day) and built one. It worked great. 2x4 A-frame sides, (3) 2x10 doug fir beam. Got a 1 ton hoist, some webbing and chains and up she went. No wobbles or creaks. Anyone interested in the details, let me know,

After the engine goes back in, the wood is going to be used in the basement for shelves and to start of some walls, so I was going to buy most of the lumber anyway!

I was also quite happy that after the engine was up, I had about 4" of clearance over the stern when I pulled the trailer out to lay the engine onto the dollies.

Any recommendations of work that should be done while the engine is out? I was thinking about the water pump & I think the alternator needs to be replaced. That will go for testing this week - it's original equipment.

Lumbergh 06-03-2012 10:24 PM

The start of another awesome project!

Sweet pics to document everything as you go along.

Thanks for sharing your journey.

tim79mc 06-10-2012 11:03 PM

Sorry for no pics or updates - I've been helping out the lake mates getting the slalom course ready and in - brownie points will be needed as I still have a lot of work and need others for pulls! I've also been looking through others' posts and learning a ton. Thanks again to this site for providing a wealth of information and confidence.

I've been making some progress at night - here's an update

The pylon has been chopped. I cut it at the base, just above the steel tube that is embedded in the fiberglass. I am going to stop at the local machine shop and inquire about a stainless replacement piece that has an ID of 2.5". The pylon OD is 2.5, so if I can sleeve the pylon with an "extended" bottom bracket, this might work out well.

I did some budgetary calcs on Seacast vs. stringer replacement and decided to go with the replacement route. Seacast/Nidacore was about $200 for 5 gals and I was looking at about 2x the cost. After cutting part of the secondary stringer on the port side, I decided to cut the whole stringer out and do the replacement.

The secondary stringer is out - I used an oscillating multi-tool - it worked awesome. Maybe a bit slow, but it created chips, not dust to blow all over the place and the flush cut blade made it easy to get close to the hull. After the stringer was out, the fiberglass was completely detached from the wood and the top half of the stringer just fell apart. The bottom was soaked in water.

I ordered medium cure epoxy from US Composites. Couldn't beat their price and the 7+ gallon kit looked like the right amount for the whole project. I'm planning to use 18oz roving to join the stringers to the hull - this is similar to the material that was used for the factory stringers. Two more layups of 8oz - 12" wide then 4" wide to reinforce the joint to hull.

I've taken measurements for the stringer positions based off the transom and centerline. I placed my laser level along the centerline and took note of the positions - I could see by eye that the stringers were NOT centered on the hull, so measuring this should be important. The engine is skewed to the port side. I had read in another thread that someone straightened everything out, but I suspected the MC did this for a reason. Another thread confirmed this - the skew of the drivetrain helps to counter the prop steer, so dimensions noted. I've got the entire engine manual for the alignment process, so hoping this goes well after repairing the stringers.

I've also blocked the trailer so the floor is level. This lets me get the height of the stringers right when I dry fit them. Because they are so rotted, I don't have a template, so I will be working a few nights to get the right shape.

tim79mc 06-26-2012 10:01 PM

Not much progress since the last update. The slalom course is in and I've been skiing with friends... It's not the same as my own boat, but I can't stay in the garage while everyone else is having fun.

My epoxy and fiberglass came in - quick shipping by US Composites. I did my first "practice" layup on my old beat up canoe - seemed fairly easy.

I finished cleaning up the bow area of stray fiberglass panels that formed the bulkhead where the foam filled against. The bow area is clear of all old foam and bulkheads, ready to become a storage area. I put a single coat of epoxy over the bow hull area to help wet out some of the fiberglass that had become exposed and white because of constant contact with water over 30+ years. The foam was waterlogged.

The Tyvek suit is working out great for keeping me itch free and the goggles and respiratory let me go to town with cutting, grinding, rolling epoxy, etc. It's great to be finished with a stint, take off the gear and be able to sit down on the couch with a beer.

I started cutting support members for the bow floor - what a pain. I'm using cardboard for the template - first few cuts were crappy, getting better.

This weekend will be a full on work weekend on the boat. I've got the supplies, now just need to get to work. Hopefully some good pics coming soon.

Lumbergh 06-27-2012 11:09 AM

Additional pics are required. Here, I'll help:

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