Fiberglass engine/ swim platform question

fishinonthebrain · #1 10-19-2012, 06:27 PM

I am in the process of designing a engine bracket/ swim platform like Kneedeep and more recently Strick has fabricated for my boat.

The question is for either one of you guys or anybody else that has fabricated one simular.

How are they holding up?
If you were to build another one would you do anything different?

This is the engine bracket/ swim platform I am refering too.

http://www.classicseacraft.com/commu...ENGINE+BRACKET

strick · #2 10-20-2012, 01:14 AM

That was the first engine bracket I made. It was made with epoxy. I would NOT do that again. They hold up fine with just polyester resin. That bracket has a suzuki df250 hanging on the back of it and is still trucking along according to the owner of the boat who I keep in touch with from time to time. When you make your molds make sure they are square and brace them like you would see a boat mold being built and you will have no problems.

strick

fishinonthebrain · #3 10-20-2012, 08:41 AM

Quote:

Originally Posted by strick

That was the first engine bracket I made. It was made with epoxy. I would NOT do that again. They hold up fine with just polyester resin. That bracket has a suzuki df250 hanging on the back of it and is still trucking along according to the owner of the boat who I keep in touch with from time to time. When you make your molds make sure they are square and brace them like you would see a boat mold being built and you will have no problems.

strick

Why not epoxy?

strick · #4 10-20-2012, 03:55 PM

$$$$$ and not necessary.

strick

Bigshrimpin · #5 10-20-2012, 04:37 PM

Holy smokes . . . that was 2004 . . . where did the time go????

Like Strick said . . . use poly . . . cause it takes about 10 - 12 gallons of resin to make one with a swim platform.

This one hasn't had much use and there is not a stress crack in it. This boxy design takes less material and less brain power to build.

The red one I made is still kicking around on a seacraft.

The one I made for Hermits Heron has had some problems, cause I added too much beer and used some experimental fabric (which wasn't a good choice). Hermit has to do some repairs to one section, but it's still holding up after a full bass season 225 ficht. Stringer design is important . . . I like one big thick stringer down the middle to the top of the tub.

fishinonthebrain · #6 10-20-2012, 09:41 PM

Quote:

Originally Posted by Bigshrimpin

Holy smokes . . . that was 2004 . . . where did the time go????

Like Strick said . . . use poly . . . cause it takes about 10 - 12 gallons of resin to make one with a swim platform.

This one hasn't had much use and there is not a stress crack in it. This boxy design takes less material and less brain power to build.

The red one I made is still kicking around on a seacraft

The one I made for Hermits Heron has had some problems, cause I added too much beer and used some experimental fabric (which wasn't a good choice). Hermit has to do some repairs to one section, but it's still holding up after a full bass season 225 ficht. Stringer design is important . . . I like one big thick stringer down the middle to the top of the tub.

How many layers of glass did you use? Is 1708 ok I have a bunch of that around?

Bigshrimpin · #7 10-21-2012, 04:17 PM

1708 8 layers. This is a really rough idea of how I cut the fabric in 4 pieces overlapping the bottom and taping the corners . . . Strick does it a bit differently.

strick · #8 10-21-2012, 05:17 PM

I usually put down two layers of 1.5oz matt as the skin then keep adding 1808 or 1708 till I get the desired thickness. Desired thickness for me is 3/8" thick with corners reinforced to about 5/8"-3/4" thickness.

strick

martin · #9 10-21-2012, 09:17 PM

Thbanks guys i was just asking the same questions

Bushwacker · #10 10-22-2012, 03:10 PM

Quote:

Originally Posted by fishinonthebrain

. . . If you were to build another one would you do anything different? . . .

There is a bit of a stress concentration at the ~90 degree angle between the side of the engine mounting surface and the aft face of the swim platform (right where rub rail stops in picture below). A 45 degree fillet in that area would significantly reduce the stress there. Or it might be easier to just extend the swim platform out to the AFT surface of the engine mount/flotation tub. This would also eliminate the stress concentration and create a slightly larger swim platform for same motor setback distance. AND consider putting a rub rail around edge of bracket - trust me, you will be glad you have that when docking around barnacle encrusted pilings!