Swim Platform Support Rod Install Problem

[p1mlb03]

I have a 97 Chaparral 1930 SS that I installed a swim platform on today. When I went to mount the support rods I drilled the first hole and found out (the hard way) that there is no structure behind the fiberglass. After looking at it I assume that it is due to the extended V plane as the transom is recessed and the "extended V Plane" is basicly a hollow cavity with foam. I have seen plenty of these extended V plane Chaparrals with platforms on them. Has anyone run into this issue and how did you manage to mount the supports? I was looking through some Chaparral pics and saw one platform with no support rods installed, is this an option? I did make some 3x3x 3/16 SS backing plates that I used on both sides in the transom tunnel area and extra large fender washers on the rest when mounting the platform itself. Looking for ideas and opinions, all very much appreciated.
Thanks, Mike

 

[Drowned Rat]

Re: Swim Platform Support Rod Install Problem

You came up with the right answer. Backing plates are what the professional installers use. Plates, not washers. Typically thick Teflon plates are used so you dont run into issues with the corners digging into the fiberglass. A SS plate is fine I'm sure as long as you round the edges and corners. If you use Teflon, also use washers. Do not install the platform without the supports, it will fail the first time you put any weight on it. There is an incredible amount of leverage on those things both from weight on top and water pushing up from beneath. Good luck and have fun, looks like a normal install to me..

Oh, and gobs of 3M 5200!

 

[Bob's Garage]

Re: Swim Platform Support Rod Install Problem

I have a 97 Chaparral 1930 SS that I installed a swim platform on today. When I went to mount the support rods I drilled the first hole and found out (the hard way) that there is no structure behind the fiberglass. After looking at it I assume that it is due to the extended V plane as the transom is recessed and the "extended V Plane" is basicly a hollow cavity with foam. I have seen plenty of these extended V plane Chaparrals with platforms on them. Has anyone run into this issue and how did you manage to mount the supports? I was looking through some Chaparral pics and saw one platform with no support rods installed, is this an option? I did make some 3x3x 3/16 SS backing plates that I used on both sides in the transom tunnel area and extra large fender washers on the rest when mounting the platform itself. Looking for ideas and opinions, all very much appreciated.
Thanks, Mike

So, from what you are saying, you are not able to reach the back side of the mounting location in order to use a backing plate?

How about this? Not the best solution but it may be up front cost effective if sealed really well. But I don't like the potential for water intrusion. http://www.iboats.com/1-4-20-Size-Stainless-Steel-Toggle-Bolt-Anchors-6-pack-Garelick

However, I found this option http://www.weldmountsystem.com that looks perfect and appears to be a viable alternative for any place a below waterline screw needs to be used. But it is expensive upfront. The payoff would be no concerns about water intrusion.

Another possibility would be, depending on thickness of the fiberglass "skin", to drill a slightly oversized hole and pack it with shredded chopped mat soaked in resin until you can't get any more in. After it hardens drill the correct size hole and insert the screw. The packed glass will have hopefully mushroomed behind the "skin" give you, in effect, a glass backing plate. I have done this on old transoms, successfully, but not on new ones.

Good luck.

 

[p1mlb03]

Re: Swim Platform Support Rod Install Problem

So, from what you are saying, you are not able to reach the back side of the mounting location in order to use a backing plate?

How about this? Not the best solution but it may be up front cost effective if sealed really well. But I don't like the potential for water intrusion. http://www.iboats.com/1-4-20-Size-Stainless-Steel-Toggle-Bolt-Anchors-6-pack-Garelick

However, I found this option http://www.weldmountsystem.com that looks perfect and appears to be a viable alternative for any place a below waterline screw needs to be used. But it is expensive upfront. The payoff would be no concerns about water intrusion.

Another possibility would be, depending on thickness of the fiberglass "skin", to drill a slightly oversized hole and pack it with shredded chopped mat soaked in resin until you can't get any more in. After it hardens drill the correct size hole and insert the screw. The packed glass will have hopefully mushroomed behind the "skin" give you, in effect, a glass backing plate. I have done this on old transoms, successfully, but not on new ones.

Good luck.

Correct, no access to be able to thru bolt the supports.
I like the weld mount system, I have not seen these before. I did something similar on my trailer rebuild. I did not want to drill holes to mount brake lines and wiring so I bought wire loom holders and cut the 2 sided tape off and used SEM panel adhesive to mount them. I also bonded diamond plate to the platforms on the trailer. SEM is what body shops use to mount qtr panels on cars. I was thinking about using this same concept last night making a plate and stud out of stainless (I have a Miller TIG) and using SEM to bond it. But I would test bonding to gelcoat before doing it on my boat. But looking at this weld mount system it might make more sense to buy a proven adhesive. They have several flavors of adhesive so I will do some reading to see what would be the best for my situation. Like most boaters, I hate drilling holes in the hull at all, much less below water line. I hope I can use some marine tex or something to repair the hole and then mount a stud with adhesive directly over.
I sure do appreciate you taking the time to help me with this issue.
Thanks, Mike

 

[Bob's Garage]

Re: Swim Platform Support Rod Install Problem

Correct, no access to be able to thru bolt the supports.
I like the weld mount system, I have not seen these before. I did something similar on my trailer rebuild. I did not want to drill holes to mount brake lines and wiring so I bought wire loom holders and cut the 2 sided tape off and used SEM panel adhesive to mount them. I also bonded diamond plate to the platforms on the trailer. SEM is what body shops use to mount qtr panels on cars. I was thinking about using this same concept last night making a plate and stud out of stainless (I have a Miller TIG) and using SEM to bond it. But I would test bonding to gelcoat before doing it on my boat. But looking at this weld mount system it might make more sense to buy a proven adhesive. They have several flavors of adhesive so I will do some reading to see what would be the best for my situation. Like most boaters, I hate drilling holes in the hull at all, much less below water line. I hope I can use some marine tex or something to repair the hole and then mount a stud with adhesive directly over.
I sure do appreciate you taking the time to help me with this issue.
Thanks, Mike

I would suggest using the "stuffing of fibers into the hole method" for the initial fill and top off the final skim coat with actual gelcoat. Marine Tex is not really very strong nor reliable, imho. I know a lot of members like it, but I have always found it lacking in lonevity, and brittle. Course you will be covering it with the stud so you could rationalize that it is covered and not need either, just fill to the surface with glass and sand smooth.

The surface that you bond to for the stud should be one that wont let go (as you obviously are aware, which is why I suggest NOT using Marine Tex. If I am wrong, no harm/no foul, but If I am right....

Let us know what you decide and how you proceed. I would al;so like to get a "read" on the viability of the Weld Mlount system.

Bob

 

[p1mlb03]

Re: Swim Platform Support Rod Install Problem

I would suggest using the "stuffing of fibers into the hole method" for the initial fill and top off the final skim coat with actual gelcoat. Marine Tex is not really very strong nor reliable, imho. I know a lot of members like it, but I have always found it lacking in lonevity, and brittle. Course you will be covering it with the stud so you could rationalize that it is covered and not need either, just fill to the surface with glass and sand smooth.

The surface that you bond to for the stud should be one that wont let go (as you obviously are aware, which is why I suggest NOT using Marine Tex. If I am wrong, no harm/no foul, but If I am right....

Let us know what you decide and how you proceed. I would al;so like to get a "read" on the viability of the Weld Mlount system.

Bob

I called weld mount systems and they do not recommend using their adhesive directly on gel coat. They said you would need to grind down to the glass; not something I want to do. There is not enough room inside the boat to install access plates to be able to get to the area to thru bolt. So what I ended up doing was making SS 3x3 plates and adhered them with SEM panel adhesive. I taped off the area and scuffed the gelcoat and plate with 60 grit to give the adhesive something to bite. I mounted the rods through the plates and into the hull using lots of 5200 in the holes and around the bracket and plate.

 

[Alwhite00]

Re: Swim Platform Support Rod Install Problem

Looks great, nice job.

LK