Permatrim caused cav plate to crack?

[12Parker2320]

I’m sure this topic has been discussed many times but I couldn’t find any consistent answers. After my last trip chasing salmon in typical PNW squared sea state conditions I noticed my cav plate was cracked all the way through more than half the plate. The permatrim was the only thing holding the cracked piece together. Also noticed one of the nyloc nuts was missing and several of the nyloc fittings were cracked or missing. My suspicion is the permatrim caused the cav plate to crack in the first place. The permatrim was added by the previous owner and I know many swear by them. I also know many folks believe you should raise the motor and re prop to a 4 blade. Regarding the fix I’ve seen some have used jb weld and epoxy which seems like a band aid job to me. I have a guy that can weld aluminum but I’m concerned the heat generated could negatively affect seals or something else in the lower unit. Any advice appreciated. Pics are attached

 

[Puck-n-Fish]

That shouldn't be a big deal for a competent welder. The cav plate is thinner and not very close to the sealing areas. You will need to remove the permatrim, so use the holes to bolt a heat sink in place to help keep it cool and aligned if you need. Most importantly, make sure the crack is properly prepped and cleaned, plenty of tack welds, and have the welder take their time.

 

[12Parker2320]

That shouldn't be a big deal for a competent welder. The cav plate is thinner and not very close to the sealing areas. You will need to remove the permatrim, so use the holes to bolt a heat sink in place to help keep it cool and aligned if you need. Most importantly, make sure the crack is properly prepped and cleaned, plenty of tack welds, and have the welder take their time.

Thanks for the response. From what I understand the prep work is crucial and the work needs to be done on bare aluminum. In regards to the heat plate do I put it underneath the cav plate when welding the top and then place it on top of cav plate when welding the bottom? Or am I not understanding this correctly. Hoping my welder knows

 

[Mpellet]

Thanks for the response. From what I understand the prep work is crucial and the work needs to be done on bare aluminum. In regards to the heat plate do I put it underneath the cav plate when welding the top and then place it on top of cav plate when welding the bottom? Or am I not understanding this correctly. Hoping my welder knows

I hate to sound negative but If the permatrim cracked the original cav plate, I can’t see how it doesn’t crack the cav plate again after you have it welded.

 

[Puck-n-Fish]

Because the bolt was missing...maybe the bolt came loose or stripped over time and the resulting uneven stress that transferred to the cav plate is what broke it?
For the welder, either side is fine. Probably put it on the backside so the welder has easy access to the weld.

 

[12Parker2320]

Because the bolt was missing...maybe the bolt came loose or stripped over time and the resulting uneven stress that transferred to the cav plate is what broke it?
For the welder, either side is fine. Probably put it on the backside so the welder has easy access to the weld.

That was my suspicion as well but I’ve heard of many a case where these aluminum permatrim or hydrofoil have resulted in cracked cavitation plates. So I’m not sure, could be the cab plate cracked and then worked the nuts lose because of movement

 

[12Parker2320]

I hate to sound negative but If the permatrim cracked the original cav plate, I can’t see how it doesn’t crack the cav plate again after you have it welded.

No worries it’s not my intent to keep using the permatrim I’m just looking for advice or past experience from anyone who has done this repair

 

[Bodick93]

My directions said to mount it under the AV plate.

 

[12Parker2320]

My directions said to mount it under the AV plate.

I had a hydrofoil on my last boat with a yami 150 and it mounted under the cav plate as well. This permatrim was on the boat when I bought it. Are you running the same permatrim on a similar size ob? And do you have pics?

 

[Bodick93]

19 F300. I just took it back off. I wanted to see how it ran with just the Rev-4 17.
One mod I made was to cut the cross member of the permatrim. I didn't like that it blocked the trim anode scoop.
My motor too readily ventilates now without it, since I raised my motor two holes. It is going back on when my black life-seal gets here. I will take a picture or two and post up.

Do you have a 4.2 liter?

 

[12Parker2320]

19 F300. I just took it back off. I wanted to see how it ran with just the Rev-4 17.
One mod I made was to cut the cross member of the permatrim. I didn't like that it blocked the trim anode scoop.
My motor too readily ventilates now without it, since I raised my motor two holes. It is going back on when my black life-seal gets here. I will take a picture or two and post up.

Do you have a 4.2 liter?

Yup 2013 4.2L, same motor. So you raised your motor and went with a rev tech 4 blade. How did you like that vs the permatrim and lower motor. I’m in northern CA and our sea state is rarely great. I was concerned about ventilating as well in a following sea if I lowered the motor

 

[Tunify]

The Permatrim that came with my 2320 is also mounted below the AV plate. It is also bedded using a generous amount of adhesive. (5200?) I could see how top mounting, combined with possibly loose screws could put some uneven loads on the AV plate.

 

[12Parker2320]

The Permatrim that came with my 2320 is also mounted below the AV plate. It is also bedded using a generous amount of adhesive. (5200?) I could see how top mounting,View attachment 33065 combined with possibly loose screws could put some uneven loads on the AV plate.

Interesting thank you. I will call permatrim and make sure it should be mounted below

 

[warthog5]

What I see.......It was installed wrong and the crack was caused by that......Look at that white shim in the back. It's making the Permitrim stand off the cavitation plate in one spot. Now the fastners are being pulled tight , trying to bend the metal.....and the cracked the piece. The Permitrim did not have even support .

 

[Bodick93]

I would say most of the pressure would be on the outer rear tip of the permatrim, and therefore the rear screws with the top mount. When the one screw came off, that put more pressure on the other screw resulting in the break.

 

[knotflying]

From the Permatrim instructions;
Place the Permatrim over the top of the AV plate. Make sure the Permatrim is straight. The Permatrim should be mounted as close to the raised section as possible without lifting the Permatrim off of the AV plate. (The Permatrim in the picture is being installed on a single engine catamaran style boat and needed to be mounted further aft. This is not the norm. The Permatrim should be against the raised section.)

Once the Permatrim is in place use a clamp, or a extra hand, to keep the Permatrim in place while you drill through the two holes you just made in the AV plate to mark the Permatrim with the drill bit. Do not attempt to drill completely through. Remove the Permatrim and drill 1.4 holes through where you marked. Temporarily mount the Permatrim using two bolts, but tighten the bolts only enough so that they keep the Permatrim in place for drilling the remaining holes.
Click here for full instructions

 

[Bodick93]

Yup 2013 4.2L, same motor. So you raised your motor and went with a rev tech 4 blade. How did you like that vs the permatrim and lower motor. I’m in northern CA and our sea state is rarely great. I was concerned about ventilating as well in a following sea if I lowered the motor

I didn't run it in rough water with the motor low and the Rev 4 installed. I had read that raising the motor was sooo great and bought into the hype. There is certainly some benefit to have the motor a little higher out of water (clearance). Mine really doesn't ventilate with the motor high and Permatrim installed, so it is going back on.

 

[Bodick93]

From the Permatrim instructions;
Place the Permatrim over the top of the AV plate. Make sure the Permatrim is straight. The Permatrim should be mounted as close to the raised section as possible without lifting the Permatrim off of the AV plate. (The Permatrim in the picture is being installed on a single engine catamaran style boat and needed to be mounted further aft. This is not the norm. The Permatrim should be against the raised section.)

Once the Permatrim is in place use a clamp, or a extra hand, to keep the Permatrim in place while you drill through the two holes you just made in the AV plate to mark the Permatrim with the drill bit. Do not attempt to drill completely through. Remove the Permatrim and drill 1.4 holes through where you marked. Temporarily mount the Permatrim using two bolts, but tighten the bolts only enough so that they keep the Permatrim in place for drilling the remaining holes.
Click here for full instructions

Interesting. I didn't just arbitrarily decide to bottom mount it. Matter of fact, it wouldn't even go into position if top mount was attempted, because of the little cross member. They obviously did a redesign.

 

[Ozdogg]

From the Permatrim instructions;
Place the Permatrim over the top of the AV plate. Make sure the Permatrim is straight. The Permatrim should be mounted as close to the raised section as possible without lifting the Permatrim off of the AV plate. (The Permatrim in the picture is being installed on a single engine catamaran style boat and needed to be mounted further aft. This is not the norm. The Permatrim should be against the raised section.)

Once the Permatrim is in place use a clamp, or a extra hand, to keep the Permatrim in place while you drill through the two holes you just made in the AV plate to mark the Permatrim with the drill bit. Do not attempt to drill completely through. Remove the Permatrim and drill 1.4 holes through where you marked. Temporarily mount the Permatrim using two bolts, but tighten the bolts only enough so that they keep the Permatrim in place for drilling the remaining holes.
Click here for full instructions

Thank you, Knotflying. I was looking for my Permatrim instructions to verify the install. I installed my Permatrim on top of the AV plate and so far no issues.

 

[Bodick93]

Knowing that the trim tab bolt is accessed through the rubber cover on top, you can see how this model would not even fit on top of the AV plate. There was clearly a redesign. This is on a '19 4.2 liter.