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1972 mx-15 project

sirdrew420

New member
i just purchased a 72 mx-15 for a hell of a deal $375 with a trailer. a few problems i would like to run by anyone. Foam in the front is soaked so i am goin to take it all out. Then i have some softness under the small sub floor in the center. the decay is in the wood between the outer layer on the bottom of the hull and the fiberglass on top of the wood in the floor. Wondering what i should do? I am also looking for a windshield for a 72 mx-15, glass and frame.
 
It depends on whether or not you want to put some serious hours into the project. I would just because it will increase the value for resale. these boats are classics somebody is always looking for one.
How are the seats and carpet?
 
I restored a 73 mx-15 and really enjoyed it, it's a labor of love but since it's so small its much easier than a big 21' boat. Mine did not have any foam in it at all, so I'm not sure what you mean by that, but the floor and transom were shot. the floor and front support wall was easy, the transom was difficult. It's a fun boat to drive and mine moves pretty good with an old V-4 evinrude on it. The boat is short and naturally light in the front end, a big motor makes it hard to keep the nose down and the boat loves to go fast and airborne in the rough water. I highly recomend putting a new floor in it and also adding some fiberglass to under the deck near the dashboard in the corners, it's weak there and after some time starts to come loose, you can see mine by clicking on my mx-15 page, shane
 
Drew, Go for it, Fix it up. I did my first floor and stringer job last winter. I had no idea what I was doing or what I was getting into. Once I got started I enjoyed it. I had a good time working on my boat. If it's wet you will need to deal with the problem at some point in time. I say tear into it now, You will do fine
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Thanx for all the support i am gonna tear in to it. I will be puting some pic on here tomarrow so u guys know what i am dealing with.
thanks again
 
Tearing in to the hull today, got the floor out and the laminated wood in the hull on one side is soft. Wondering if i should repalce it? Also there are some soft spots by the holes where the motor mounted on the transom, with that in mind should i replace the transom or fill the holes with some special resin?
 
Treated plywood as well as marine grade is designed to be used as is. If you fiberglass over treated or marine grade the resin will not stick very well. Add the additional cost over regular plywood and its not worth it. When going back together with new wood. Scuff new wood with 80 grit, coat the wood with thinned resin. This will allow the resin to soak into the wood and have a good mechanical bond, and seal out water. Coat both sides and ends. Make sure its sealed and it will last another 30 years.
Shoot some pictures of the soft wood in the hull. Sounds like you have a soft spot in the balsa core.
As far as the transom goes it sounds like its a bit soft. Since you have it torn down this far it would not take much more to replace the transom.
 
Will shoot some pic tonight. yes it is a soft spot in the balsa core, how would i go and fix it? the soft spot is about 3 feet long and 1 1/2 feet wide extending from the center of the boat 1 1/2 feet out from there.
 
There rally is only one way to fix the balsa core. That is to cut/grind it out. Go past the soft stuff about 6". Grind the hull smooth and glass in new balsa. They come in small squares. Once its glassed down you run glass over the top. Sealed forever.
I am sure coop could give a hand on this. I did not have to tear mine up.
 
Drew, I had a soft spot in the center of my floor as well. It was just in front of the bilge well. After cutting out all the wet black wood I let a fan blow on it for a few days. The hole ended up about 6"x6" and down as deep as the top of the pad. I filled the hole with matt and resin, put in my hard wood filler block then topped it over with matt and resin. I think that was a forever repair' hope so anyway!! Let's see some pics of the damage.
 
Originally posted by sirdrew420:
Will shoot some pic tonight. yes it is a soft spot in the balsa core, how would i go and fix it? the soft spot is about 3 feet long and 1 1/2 feet wide extending from the center of the boat 1 1/2 feet out from there.

Ok, here is how you fix bad balsa.

1. Figure out how big of an area needs repaired, and draw a mark a few inches beyond that.

2. Use some sort of cut of wheel that you can set how deep you are cutting. I have used a circular saw for this, till I found better tools. It works great. Set your depth at about 1/4inch or less, and cut around the area you have marked.

3. Use something to pry up under the edge of the glass. The only thing holding the glass down would be the good balsa that is still there. The rotten basla should give way quite nicely.

4. Set the piece you cut out aside to use as a pattern for new glass. Make your new pieces, make at least one piece the same size and the rest a few inches bigger. Use either heavy roving or biaxial cloth.

5. Use a wide wood chisel and a hammer to chip away all the balsa that is exposed. Try to get as much out as you can before you break out the grinders. Its rotten, it should come out easy.
Go to someplace like www.fiberglast.com and order some new balsa. If you cant find any locally.

6. Use a sander or a grinder to clean up the inner skin.

7. Cut 2 pieces of 1-1/2 ounce fiberglass mat. The same size as your repair area.

8. Have your glass and balsa precut, then use your brush and wet out the repair area with resin. Then lay one of the pieces of 1-1/2 ounce mat on some cardboard and wet it down with resin, then take it and place it down in your repair area, and bruch out an LARGE air bubbles. Don't worry about any small ones they don't matter for what you are doing.

9. Take your precut balsa and brush resin on the side that does not have the fabric holding it together, then quickly place it in the repair area over the still wet glass mat that you just placed in there. Use your hands to press it in as best as you can. After you get it inplace. Take some wax paper and cover the entire repair, then cover that with cardboard. Place any kind of weight you can find on top of the card board. Books, magazines, newspapers, anything.

10. Now walk away for at least 2 hours. Have lunch, drink a wobblypop, whatever, just leave it alone for at least 2 hours.

11. Now remove the weights, the cardboard, and the wax paper should have kept the cardboard from sticking, you are ready to continue.

12. Use a filler like duraglass to fill in around the repair area, there will be some gaps between the old area and the new area. Fill these areas flush with the level of the new balsa, don't fill them to the level of the old glass layer. Let this set up. Then sand smooth if needed.

13. Brush a layer of resin onto the new balsa over lapping onto the old glass. Wet the other piece of 1-1/2 ounce mat on the cardboard again, then place the mat onto the repaired area. Brush out the LARGE air bubbles ONLY right now. Take the piece of biaxial glass or roving, that is the same size as the repair and wet it out on the cardboard. Then place it on top of the still very wet mat. Use a plastic or rubber squeege to work all the air bubbles to the sides and out. Do this as good as you can.

14. Take the last piece of biaxial or roving and wet it out on the cardboard, the place it over the still wet glass you just laid down.
Use a squeege to work all the air bubbles to the sides and out. Keep working at it until all the air is gone or the resin starts to set up.

15. Drink another wobblypop, cause you just fixed your boat.
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Yea, what he said.
I was going to post that last night, but you described what I was going to say. Fun stuff. Wear the disposable rubber gloves to help keep the resin off your hands.
 
Hmmm, thanks Gus. I should have made that the first step, wear all appropriate safety gear, gloves, mask, glasses, etc.
 
Thanx guys that was exactly what i needed to know. i am stil working on getting some pics of the boat. i will get on it tonight.
Thakx Again

Drew
 
A 72 mx 15 eh? They are an ok boat. My favourite, but still only ok. I have probably the most original one still around, looks like it just came out of the showroom. Has a 74 J block merc on it (identical to a 1500XS, just high water pickups which work better than the XS low waters anyways, 155hp) and its a beautiful boat. With the short shaft it runs right around 70 TRUE mph. When the boat was new, my dad blueprinted the hull and put a slight rocker in it. So now the boat hops at midrange but helps to get the hull out of the water faster and once you trim out of the rocker it just hangs. I have the same boat without a rocker and it ran slower because the hull wouldnt release as well.

These boats are fun to drive, but since they don't have a pad you really have to know what you are doing to run them top end. Also THEY DON'T TURN!!!!!!! If you don't remember anything else, REMEMBER....THEY DON"T TURN!!!!!! You have to turn extremely gradually because if you make a normal or sharp turn the boat goes right up on its side on the gunnel trim. The first time it happens it scares the shit out of you. We have had people thrown out of those boats because of this....be extremely careful.

When you repair the boat, do everything once and dont' do it again. What I mean is if the trasnsom is rotten, do it now. Take the extra time to take the deck off of the boat because you CAN NOT remove the transom from the back. If you cut the back out of the shell, the boat is basically scrap. I know a lot of you have done this but its not as good as having the old shell. No matter what resin you use you cannot bond to that old shell as good as it needs to be in that area. We have had to replace whole hulls on Hydrostreams for people because they cut the back out and at close to 100MPH a transom that has the back cut out will fail. Just remove the deck, chip out the transom from the inside, and then replace the wood. Put a couple knees in for strength too if you wish. whe doing the core, make sure you get all the air out because air pockets make the core rot. When we do cores now, we vacuum bag them into the boat so there is no chance of failure EVER unless someone pokes a hole in the hull.


As for the comment on resale value, I don't think there is much of a resale value on them. To fix them properly with core and all with new flake windshield and such,
I usually have close to $4000 into them. I have a 1972 MX 15 in my yard that I would gladly restore and make look exactly like new if someone will pay me the right money but I might as well throw my money away if I have $4000 into it and only get $2000 for it.

What I am saying is do it for the love of the boat, not the resale value.

I can get you a new windshield, I just ordered one the other day for a later model MX 15 we are rebuilding for a customer.
 
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