chautauquasun
06-19-2009, 01:46 PM
I am beginning to see some warning signs of stringer rot in my boat. Engine bolts are loosening up in the stringers and cant be tightened back down. I have been thinking about how I want to repair this without doing a complete rebuild. My floors are okay no real softspots but know that the stringers are going to need replaced at some point. I am hoping to fix the engine mounts and be able to get through this year and maybe next year before going through a rebuild.
I came across this idea on the internet. It sounds like a good repair until I redo the stringers. Any of you guys familar with this idea? It seems like it would be pretty simple to do and if it works should hold for a little while assuming there is still some wood left. Let me know what you guys think. I think it would worth a try. Any pitfalls you can see...do you think this will make it harder to remove the stringers later?
Please share your thoughts with me. Here is the fix.
Stringer Motor Mount
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I have been a fiberglass hobbiest for many years and in 1976 worked for 4 months in a fiberglass shop making master molds for sinks, tubs and shower walls from woven roven and epoxy resin. I have owned several I/O boats with rotten mounts and fixed them all the same way. If you pound a boat with bad mounts, the engine will crush the mounting floor and sink the boat. I felt if I had to go to all the trouble of removing the engine to fix the mount, I might as well sell the boat for junk, therefore I came up with a creative repair method.
I've seen repair shops rip out and splice in a new wood stringer and then glass it up. Well that's great but a lot of unecessary hassle and expense.
1. Take the motor mount off but dont remove the engine. This allows you room to work. If you repair the mounts one at a time you probably don't need to support the motor. Take a wood bit about 1.5 inches or larger depending on the boat size and drill one or more holes in the mount as deep as possible without going through the boat bottom.
2. Get a one gallon bucket a mix a thick but semi pore-able slurry of shredded woven roven and polyester resin. Pour it into the hole you drilled while using a stick to stuff the hole until it wont take any more of the slurry. On my under 20 ft boats I fixed, they took from 1/2 to 3/4 gallon per mount.
Let it set up over night and drill new motor mount holes the next day. Use a good grade of stainless or the original screws and drill the hole smaller then major diameter, but not smaller then the minor diameter of the screw. If the hole is too small you will crack the glass. On a 140 hp Volvo Pinta I used a 5/8 screw and torqued it to about 125 ft lbs, I was amazed it did not strip. Whatever you do make sure that the mixture does not cure at a higher rate then recommended. If done correctly this will be stronger than the original. Assuming you have room to work you should have about 4 hours into the job four four mounts.
Fiberglass is nasty to work with, so buy a gallon of acetone for cleaning up and a particle mask to avoid inhaling the glass fibers as you shred them. The fiber glass itches so minimize contact with the cloth, especially on your forearms.
If you want to check to see if your motor mouunts have any integrity, check the wood screws that penitrate the stringer with a wrench. Just remember they are very easy to strip in an old boat, so don't use hardly any force at all. In fact, if you see that the screw at not screwed all the way down, this is a sure sign that your stringer screws are stripped.
When I fixed the Volvo Pinta, I had already crushed the rear motor mounts in a wave jumping storm and did not know it until I got the boat home. Another five minutes of pounding would have sank the boat because every time I jumped a wave the motor would lift out of the rear mount about six inches and slam down crusing the floor.
I came across this idea on the internet. It sounds like a good repair until I redo the stringers. Any of you guys familar with this idea? It seems like it would be pretty simple to do and if it works should hold for a little while assuming there is still some wood left. Let me know what you guys think. I think it would worth a try. Any pitfalls you can see...do you think this will make it harder to remove the stringers later?
Please share your thoughts with me. Here is the fix.
Stringer Motor Mount
--------------------------------------------------------------------------------
I have been a fiberglass hobbiest for many years and in 1976 worked for 4 months in a fiberglass shop making master molds for sinks, tubs and shower walls from woven roven and epoxy resin. I have owned several I/O boats with rotten mounts and fixed them all the same way. If you pound a boat with bad mounts, the engine will crush the mounting floor and sink the boat. I felt if I had to go to all the trouble of removing the engine to fix the mount, I might as well sell the boat for junk, therefore I came up with a creative repair method.
I've seen repair shops rip out and splice in a new wood stringer and then glass it up. Well that's great but a lot of unecessary hassle and expense.
1. Take the motor mount off but dont remove the engine. This allows you room to work. If you repair the mounts one at a time you probably don't need to support the motor. Take a wood bit about 1.5 inches or larger depending on the boat size and drill one or more holes in the mount as deep as possible without going through the boat bottom.
2. Get a one gallon bucket a mix a thick but semi pore-able slurry of shredded woven roven and polyester resin. Pour it into the hole you drilled while using a stick to stuff the hole until it wont take any more of the slurry. On my under 20 ft boats I fixed, they took from 1/2 to 3/4 gallon per mount.
Let it set up over night and drill new motor mount holes the next day. Use a good grade of stainless or the original screws and drill the hole smaller then major diameter, but not smaller then the minor diameter of the screw. If the hole is too small you will crack the glass. On a 140 hp Volvo Pinta I used a 5/8 screw and torqued it to about 125 ft lbs, I was amazed it did not strip. Whatever you do make sure that the mixture does not cure at a higher rate then recommended. If done correctly this will be stronger than the original. Assuming you have room to work you should have about 4 hours into the job four four mounts.
Fiberglass is nasty to work with, so buy a gallon of acetone for cleaning up and a particle mask to avoid inhaling the glass fibers as you shred them. The fiber glass itches so minimize contact with the cloth, especially on your forearms.
If you want to check to see if your motor mouunts have any integrity, check the wood screws that penitrate the stringer with a wrench. Just remember they are very easy to strip in an old boat, so don't use hardly any force at all. In fact, if you see that the screw at not screwed all the way down, this is a sure sign that your stringer screws are stripped.
When I fixed the Volvo Pinta, I had already crushed the rear motor mounts in a wave jumping storm and did not know it until I got the boat home. Another five minutes of pounding would have sank the boat because every time I jumped a wave the motor would lift out of the rear mount about six inches and slam down crusing the floor.