785 project - restoration work

[pascoea]

Figured I'd start a new thread for the 785 project. Some pics of what I'm up against.

Left side gunnel. Not quite sure what happened here, but she sure took a beating. I'm thinking the plan here is to epoxy in a couple slabs of fiberglass from behind, grind out the damage, build up with a couple layers of glass/epoxy on the outside. The question I have is what kind of filler/bondo can I use to finish off? Or is there something else I should be using?



The back deck. Pretty straightforward repair. The crack had kind of de-laminated the glass, so I had to use a Dremel with a small burr to cut a groove down the crack and get it to sit flat. Added a couple sheets of glass in on the inside. I'm not real happy with how it laid down along the ridge, it didn't quite adhere like I wanted, but it should be good enough. SUPER awkward area to try and work in. Temporarily screwed on a chunk of wood to the outside to hold everything level-ish. The plan is to stand it on its end and use some 4lb density expanding foam to reinforce. Same as above, going to bevel the area back with a flap-wheel and build up a couple layers of glass/epoxy on the outside.



Where else I'm a little lost is on these kind of cracks. It looks to me like it's just the gelcoat, or maybe the outside layer of the SMC? The plan was to use the burr to cut a shallow groove into them, then just fill with a non-reinforced body filler. Is there something else I should be using instead?

[xlint89]

Sorry, I'm not a body guy. Hopefully someone else who does know will chime in.

[Myself]

For filler you could use 'Marglas", 'Pro-glass" or 'Duraglass"....all waterproof. 3M also has a waterproof marine filler. I use Pro-glass because it's what the local body supply has in stock. I've also used both the other brands with no issues. I mix in 1/4" chopped strand glass with my epoxy resin for deeper or larger fill areas. The dremel with a sanding roll makes a nice groove to fill in all those gel coat stress cracks. If you don't.....they WILL be visible after paint! You really need to get it as close to smooth as possible without any other types of filler. It's totally do-able but it uses a lot of sandpaper cause the high resin content clogs it up. Then I go over the whole thing with a 2k filler primer. It even comes in spray cans now with the catalys built into the bottom of the can......you just pop it on something then shake it up! Light sanding marks and pinholes will fill up with a couple passes of the 2k primer. And after a couple days it wet sands flat pretty nice without clogging the paper too bad.

[pascoea]

For filler you could use 'Marglas", 'Pro-glass" or 'Duraglass"....all waterproof. 3M also has a waterproof marine filler. I use Pro-glass because it's what the local body supply has in stock. I've also used both the other brands with no issues. I mix in 1/4" chopped strand glass with my epoxy resin for deeper or larger fill areas. The dremel with a sanding roll makes a nice groove to fill in all those gel coat stress cracks. If you don't.....they WILL be visible after paint! You really need to get it as close to smooth as possible without any other types of filler. It's totally do-able but it uses a lot of sandpaper cause the high resin content clogs it up. Then I go over the whole thing with a 2k filler primer. It even comes in spray cans now with the catalys built into the bottom of the can......you just pop it on something then shake it up! Light sanding marks and pinholes will fill up with a couple passes of the 2k primer. And after a couple days it wet sands flat pretty nice without clogging the paper too bad.

Thank you for the thorough answer.

I had a suggestion on another forum (Facebook group) where a person was suggesting they wouldn't attempt the repair without splitting the hull. Any thoughts on that? They were specifically referring to the gunnel repair. My intent was just to dig the existing foam out of there, do my best to get a couple layers of glass/epoxy in from behind, then complete the repair from the outside. (Reinforced with 4Lb density foam once it's done.)

[Myself]

You can do that WHOLE repair from the outside. Grind/cut out the damaged glass. Use spray foam from behind to 'fill' in the void. Carve the spray foam out just under the edges so you can stuff glass down under the edges in a 'from behind' lip type approach. Brush epoxy resin into the foam and let it set up first. That will harden and seal the foam. Then add in your glass feathering out the edges. Smooth out the top and done.

[pascoea]

You can do that WHOLE repair from the outside. Grind/cut out the damaged glass. Use spray foam from behind to 'fill' in the void. Carve the spray foam out just under the edges so you can stuff glass down under the edges in a 'from behind' lip type approach. Brush epoxy resin into the foam and let it set up first. That will harden and seal the foam. Then add in your glass feathering out the edges. Smooth out the top and done.

Thank you.

[pascoea]

Finally got the rest of the crap out of the hull, gave it a good de-greasing and power wash. Didn't come quite as clean as I'd like, but HUGE improvement. Uncovered a couple areas of concern that are going to be addressed:

Looks like I'm going to have to do some light repair work underneath the ebox (?) mount:


I need to do some more investigating to figure out if it's just the epoxy coating that's cracked, or if it's lifting out of the glass.

Next one, up underneath the gas tank mounts, bit of degradation of the fiberglass, and a bunch of the coating came up.



What would a guy use to repair/recoat it? My intent is to clean up and re-coat the entire interior once I'm done with the repairs.

Lastly, the trim motor... It was pretty nasty inside, but I was able to get everything cleaned up and moving. I don't trust the motor though, too far gone. The sticker in the picture appears to be Polaris markings, not the part number of the motor itself. There was another sticker on the back of the motor, I assume it was the actual part number, but I couldn't read it. Based on a FB post it looks like a Mabuchi RS-555SH 12v motor is the proper replacement, so I have on of those on the way. Anyone have a clue what the difference between the 3RPM (slow) and 6RPM (fast) trim motors are? Is it just the actual motor, or is the gearing different? I only ask because the post I found was the "fast" motor, so I have no clue if changing this motor out will turn it to a 6RPM motor or not. (EDIT: For anyone that comes and finds this later... Here's a good thread on rebuilding these: http://greenhulk.net/showthread.php?t=220252 )

[pascoea]

I was short a couple of parts: MFD Core, Trim Box, a drive shaft, some pump parts, some random bolts, a stator/flywheel, starter, and a control PCB for the 900. So I found a better solution. Meet the newest member of the fleet, everybody's favorite, the "donor ski".



$450 bucks, delivered, with a trailer.

Cosmetically, the hull is pretty tough, but quick look appears to be structurally sound. Motor was delivered in pieces, so no clue what I've got there. I figured if I can get half the parts I need out of it I came out ahead.

(I replaced the motor on my original trim box, as outlined above, and it promptly gernaded. Not sure if I screwed up or what, but it broke a shaft and stripped a couple gears)

As you can tell from the amount of leaves, the "thinking about jet skis" season is about over up here, so we'll mostly be picking these projects up next summer. I might start the 785 engine rebuild over the winter, but it's time to turn attention to my other hobby:

https://youtu.be/wDx6A2Pixqc

https://youtu.be/cI44KmJf194

[Beernutz]

I know where I'll be taking the wife to look at lights this winter... the only problem is that she'll question how I know about them!

[pascoea]

I know where I'll be taking the wife to look at lights this winter... the only problem is that she'll question how I know about them!

Ha, no need to explain, just "happen" by. There are a couple people around here that put up some decent displays.

I usually have everything up by Thanksgiving, but probably won't have music incorporated till closer to xmas. If anyone else wants the address (Ramsey, Northwestern Minneapolis suburb) shoot me a PM.

[pascoea]

Hey all, quick update and a couple of questions.

So I happened across a local 785 hull that was allegedly only used by the dealer for racing. No prior registration, aftermarket steering setup, aftermarket sponsons, and the 1/4" ish holes in the right side of the hull that I've only seen used to mount the MSD style ignitions. It's definitely not as structurally messed up as the other one. There's Still some "rash" on the bottom that needs addressed, and the aforementioned holes drilled in the side, but a way easier project than the other one. I think think this is going to be the base for my stock 785 build. Bonus that it's got 2/3rds of a set of triple pipes and various other goodies that I can use, not bad for $100.

The questions:

1. Cover. The ladies are naked outside, and I don't like it. I'm going to like it way less once they are redone. Anyone have a source/lead on OEM (or OEM-Style) covers for these?
2. Decals. I'm going to need a full set of decals. I found a place that's doing OEM reproductions for the red (99+?) Pro, but nothing for the 97 SLX style. Any advice?
3. Jetworks valve for the exhaust. I'm going to do the "Watcon" routing, single Jetworks valve in between the main manifold and the distribution manifold up front, but it's not clear on the specific model I need. I could use some help getting the right part.

Lastly, the other update. The Christmas lights are up and running, stop by and check them out if you're in the Minneapolis area.

Cheers guys, and happy holidays.

[xlint89]

Jeez, you KNOW we need pictures. What's up with that?

What do you mean 2/3 a set of triple pipes? I'm guessing you need just 1 pipe for a complete set?

You can find OEM covers on Ebay, but that guy is charging a lot for them. Nothing wrong with generic covers.

Decals, I have no idea. Sorry

Jetworks valve should be the 3/8" one. It's not a bad idea to get a Delrin ball to use instead of the rubber one that comes with the valve. The rubber tends to stick in the closed position when it sits for a while. The Delrin doesn't stick, so if you can source 1 I'd do that. Or get in the habit of checking the rubber check ball if the ski sits for a bit prior to using the ski.

[pascoea]

Jeez, you KNOW we need pictures. What's up with that?

What do you mean 2/3 a set of triple pipes? I'm guessing you need just 1 pipe for a complete set?

You can find OEM covers on Ebay, but that guy is charging a lot for them. Nothing wrong with generic covers.

Decals, I have no idea. Sorry

Jetworks valve should be the 3/8" one. It's not a bad idea to get a Delrin ball to use instead of the rubber one that comes with the valve. The rubber tends to stick in the closed position when it sits for a while. The Delrin doesn't stick, so if you can source 1 I'd do that. Or get in the habit of checking the rubber check ball if the ski sits for a bit prior to using the ski.

As for pics, yeah, I know... I suck at life, lol. None of the old girl at home, but here's one from the prior owner. Also reminds me, came with a minty-looking seat cover, the other one I have has seen better days.



Thanks for the info on the valve, just couldn't find any concrete info on which one to use.

And on the pipes, yes, the top pipe is missing, other than that it appears to be a full set. It's in a billion pieces, so can't really be sure, but appeared to be all there.

I was really hoping to make this a "fresh off the showroom" kind of build/restoration, hence the desire for an OEM cover and at least reproduction decals. I did see someone on FB had found a complete set and was talking about sending it to the decal company to get it scanned and reproduced.  No clue if they did or not, but that would be awesome.  The "good" one I got is just beat up enough that I want to fill the divots and re-do the paint/gel coat. So not quite sure what I'm going to do if I can't find a decal set, probably just leave it nekkid.

[sdlvx]

Pretty sure that's a 97 hull because of the side wall graphics with the pro 785 logo. The 97 hulls are a little thinner than the later hulls and are prone to breakage in some spots, but I'm not sure where. Both of mine are 98s. Top deck on a pro 784 is RTM, not SMC, and the bottom is fibreglass with balsa wood core. If these hulls are in bad shape you need to make sure no water got into the balsa wood, because wet balsa will swell and ruin the rest of the glass.

You're not supposed to use polyester resin on SMC, because SMC has mold release agent throughout the whole material and the polyester won't bind well enough to last. You're supposed to use epoxy, which is a huge pain in the arse as it takes forever to cure compared to polyester. But epoxy is superior, stronger, I think lighter too. I'm assuming RTM is the same as SMC since it's basically blow molded from what I understand.

The hull (not the deck) on a pro 785 is made like a boat, where they have a one sided mold for the outside of the hull. They put mold release against the mold on the outside, then just spray the mold full until they get enough material. They have fiberglass guns that shoot a mat/resin combo.

You can get epoxy pretty cheap from uscomposites.com, I am making a Yamaha 760/JS550 conversion ski and I put an entire layer of epoxy and heavy duty glass along the entire bottom of the ski. It takes a long time to cure, it's not like polyester where you put on a lift and come back 30-60 minutes later and put on another one. You basically just do one a day. You also have to mix it like crazy, at least 5 minutes until it gets foamy.

uscomposites has everything you need to repair glass, you can even call the guy that works there and pick his brain, he's pretty smart. The epoxy lift I put on my 550 hull seems extremely strong, I recommend it even if it's a pain. But besides the long cure time it's not much different than working with polyester.

If you are doing big pieces you should get the epoxy rollers (https://www.totalboat.com/product/ec...epoxy-rollers/), put them on a clean piece of cardboard, then roll the resin into the mat with the roller. Epoxy is really runny, you don't need as much as you do with polyster resin. They have a bunch of different shapes and sizes for doing corners and stuff too.

You can also use PVC board for larger repairs, just heat it up, screw it in places, then glass over it. I learned a lot working on my 550 project, hopefully it'll be done next spring.

[pascoea]

Pretty sure that's a 97 hull because of the side wall graphics with the pro 785 logo. The 97 hulls are a little thinner than the later hulls and are prone to breakage in some spots, but I'm not sure where. Both of mine are 98s. Top deck on a pro 784 is RTM, not SMC, and the bottom is fibreglass with balsa wood core. If these hulls are in bad shape you need to make sure no water got into the balsa wood, because wet balsa will swell and ruin the rest of the glass.

You're not supposed to use polyester resin on SMC, because SMC has mold release agent throughout the whole material and the polyester won't bind well enough to last. You're supposed to use epoxy, which is a huge pain in the arse as it takes forever to cure compared to polyester. But epoxy is superior, stronger, I think lighter too. I'm assuming RTM is the same as SMC since it's basically blow molded from what I understand.

The hull (not the deck) on a pro 785 is made like a boat, where they have a one sided mold for the outside of the hull. They put mold release against the mold on the outside, then just spray the mold full until they get enough material. They have fiberglass guns that shoot a mat/resin combo.

You can get epoxy pretty cheap from uscomposites.com, I am making a Yamaha 760/JS550 conversion ski and I put an entire layer of epoxy and heavy duty glass along the entire bottom of the ski. It takes a long time to cure, it's not like polyester where you put on a lift and come back 30-60 minutes later and put on another one. You basically just do one a day. You also have to mix it like crazy, at least 5 minutes until it gets foamy.

uscomposites has everything you need to repair glass, you can even call the guy that works there and pick his brain, he's pretty smart. The epoxy lift I put on my 550 hull seems extremely strong, I recommend it even if it's a pain. But besides the long cure time it's not much different than working with polyester.

If you are doing big pieces you should get the epoxy rollers (https://www.totalboat.com/product/ec...epoxy-rollers/), put them on a clean piece of cardboard, then roll the resin into the mat with the roller. Epoxy is really runny, you don't need as much as you do with polyster resin. They have a bunch of different shapes and sizes for doing corners and stuff too.

You can also use PVC board for larger repairs, just heat it up, screw it in places, then glass over it. I learned a lot working on my 550 project, hopefully it'll be done next spring.

You are correct, both are 97 hulls. The breakage issue, from what I understand, is the back of the top-deck as aptly demonstrated by the first hull. The gunnel damage isn't typical, just the prior owner beating the crap out of it. The "new" hull appears to have been reinforced by the end user, some light spidering and chipping, but appears to be much more solid than the first one.

I appreciate the input on the balsa wood thing, I hadn't thought about the core getting wet. I wouldn't even know where to start on how to check that. It hasn't been on the water in years, so I don't know if it would have dried out by now?

As for the epoxy/polyester thing, yeah I already have a "fast" setting epoxy from Totalboat. (They have an Amazon store, super handy.) The repair manuals suggest the same repair techniques and materials for both the RTM and SMC