Transom strength for hydraulic jackplate

NSBCraig

Lieutenant Commander
Joined
Aug 21, 2007
Messages
1,907
Re: Transom strength for hydraulic jackplate

nice answer from cmc.

All plates have a larger contact point on the transom then a motor though not just theirs.

As for the pump being in the boat or plate I'd much rather it be in the boat. Never mind the extra install, for the money your spending do it right.

My TH marine plate is electric and the actuator is in the plate. The boat never hit saltwater (it was my brothers so I know where it was after I installed the plate for him) until I had it and the deterioration of the actuator housing was already worse then I'd like.

I'm already planning on upgrading it to hydraulic with a pump in the boat.

Just something to think about.
 

Mark42

Fleet Admiral
Joined
Oct 8, 2003
Messages
9,334
Re: Transom strength for hydraulic jackplate

If it was my project, I would mount the jack plate and motor. Then check the flex in the transom. If its more than it was without the jack plate, add a few pieces of pressure treated plywood wrapped in glass to the inside of the transom to spread the strain across a larger area. Then re-test for flex.

Don't forget to use pressure treated plywood. It gives you the extra insurance against rot when the resin cracks (it will eventually ) or the holes to mount the jack plate leak (they will eventually) that the wood will not rot and will most likely outlast your ownership of the boat. And then the next owner will not have to worry about rotten wood.
 

Mark42

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Oct 8, 2003
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Re: Transom strength for hydraulic jackplate

resized100_2337.jpg

Man! Talk about a Frankenstein boat! Additional flotation welded on the back, some trim tab looking things added to the extra flotation boxes, and more stuff bolted onto the cavitation plate! Also looks like the transom was raised (its higher than the gunnels), and then some angle bracing added to the corners to help hold it all together..... Holy cow! I guess the original setup did not do what the owner wanted, and then it didn't handle the way they expected after modifying it..... All that stuff..... Boy, oh boy..... Hope it does what they want.

My guess is the motor is a higher HP than than the boats original rating.
 

69rrvert

Petty Officer 1st Class
Joined
May 9, 2010
Messages
211
Re: Transom strength for hydraulic jackplate

Man! Talk about a Frankenstein boat! Additional flotation welded on the back, some trim tab looking things added to the extra flotation boxes, and more stuff bolted onto the cavitation plate! Also looks like the transom was raised (its higher than the gunnels), and then some angle bracing added to the corners to help hold it all together..... Holy cow! I guess the original setup did not do what the owner wanted, and then it didn't handle the way they expected after modifying it..... All that stuff..... Boy, oh boy..... Hope it does what they want.

My guess is the motor is a higher HP than than the boats original rating.

Mark,

Since you obviously don't know anything about a boat manufactured by Alweld or a flats boat in general, let me try and school you right quick. I agree, it's not a pretty boat, but that's not it's purpose. With the exception of the trim tabs and larger tunnel, the boat is 100% factory. The "raised transom", "the angle bracing added to the corners to help hold it all together", and the so called "welded on floatation boxes", are all factory. You are correct on one thing though, the floatation boxes are welded on because fiberglass and resin just does not hold up in this application with aluminum. That is why they are welded on. The boat is designed to run in shallow water (about 6") and does a damn good job at it. I added the trim tabs and modified the factory tunnel myself. The purpose of the trim tabs are to keep the boat from porpoising and add lift to the stern while taking off. The purpose of the tunnel is to allow me to jack the prop up above the bottom of the hull if I need to. Again, this works exceptionally well and allows the boat to get up in about 12" to 14" of water. I added a vent to the tunnel also. The purpose off this "vent" is to keep the tunnel from creating a vacuum. The "stuff" that is on the cavitation plate is called a Shallow Blaster. The purpose of the Shallow Blaster is to catch the water coming out of the tunnel, redirect that water over the prop, and help hold that water over the prop and water intake on the motor when the motor is jacked up. It also helps prevent prop cavitaion and adds bow lift as well. This works exceptionally well also. When running in shallow water you use the water compression that is generated between the bottom of the hull and the bay floor to create additional lift. The "welded on" (remember, can't use fiberglass) floatation boxes aid in this as well. Also, you missed my home built stainless steel skeg gaurd that I made. As a boat owner, we are always trying and doing things to our boats to make them better, and "boy, oh boy" does it ever do exactlly what I want it to do now. The only thing I would like to do to it now, would be installing a new Evinrude outboard on it, but the '84 115 Evinrude that is on it runs like top so why change it. One thing about it though, I can take my junk anywhere you can go, but I dare you to even attempt to follow me. One last thing, it is rated for a 115 HP engine. Now, back to the original purpose of this thread. Thanks, Steven
 

69rrvert

Petty Officer 1st Class
Joined
May 9, 2010
Messages
211
Re: Transom strength for hydraulic jackplate

Ahh heck Mark, come on and follow me around, we could use a new rebuild thread on here.
 

bear_69cuda

Commander
Joined
Oct 10, 2008
Messages
2,109
Re: Transom strength for hydraulic jackplate

Please dont get me wrong .. as I know I have a knack of sounding ..erm.. offish.. but..

Are you planning on being completely responsible for this mod ? or do you have to have a "certified" guy install this.

I know what your going to say..but..I have done add-on mods that have in Writing to say "If a certified tech performes the installation we will warranty any damage done to the structure of the boat" ( sorry cant tell you who or what mod...lets just say its for ease of transom swimming applications :) ).

Or is this warranty a non issue..

YD.

Hi Doc,

Yes I was planning on installing the jackplate myself. Only after my local boat builder agrees the transom is strong enough for this mod. Not sure if it makes a difference who installs the plate as Nautic Group will not warranty the transom after the mod anyway (if it fails due to jack plate) I only want to make sure it's safe, and that it does not fail at all. I have more confidence in this mod after hearing what the president of CMC plates said about one of there employee with one on his Hurricane, with 250 HP for 4 years and no issues. I plan on using backing plates, and possibly reinforcing the transom if needed.

I do appreciate, and respect your offishness brutha!
 

NSBCraig

Lieutenant Commander
Joined
Aug 21, 2007
Messages
1,907
Re: Transom strength for hydraulic jackplate

What ever you do don't jury rig your boat putting strips of PT on the back of your transom!

Wow the complete nonsense that gets posted on this forum.

If your transom is sound your fine mounting a jackplate on it. You already got this answer from the people who know the most about it (Bobs and CMC).

If your transom is NOT sound it needs to be fixed. Don't B.S. it and then mount a jackplate to it.

Wow some people just get on a roll of craziness and just start letting it fly!

Let's go back to what your only real concern was- are you worried about the warranty being denied because of you installing a jackplate?

If that doesn't bother you then go for it and have fun! Of course do the install right and be sure to use all the right parts.
 

bear_69cuda

Commander
Joined
Oct 10, 2008
Messages
2,109
Re: Transom strength for hydraulic jackplate

What ever you do don't jury rig your boat putting strips of PT on the back of your transom!

Wow the complete nonsense that gets posted on this forum.

If your transom is sound your fine mounting a jackplate on it. You already got this answer from the people who know the most about it (Bobs and CMC).

If your transom is NOT sound it needs to be fixed. Don't B.S. it and then mount a jackplate to it.

Wow some people just get on a roll of craziness and just start letting it fly!

Let's go back to what your only real concern was- are you worried about the warranty being denied because of you installing a jackplate?

If that doesn't bother you then go for it and have fun! Of course do the install right and be sure to use all the right parts.

Thanks Craig,

If the transom needed reinforcement I would have my local boat builder do it right. I never cobble or skimp on anything I do... The boat has only been used one summer, and I'm sure the transom is solid. I raised the Yamaha 3 weeks ago, and the wood was bone dry in the bolt holes. I not worried about the warranty I just want it to be safe. I'm really looking forward to this mod, as I love tweaking.... Now I just need to wait for 4.5 months for the snow and ice to melt. :redface:
 

NSBCraig

Lieutenant Commander
Joined
Aug 21, 2007
Messages
1,907
Re: Transom strength for hydraulic jackplate

You know it's not snowing but man is it too cold to do any boating right now.
 

Cadwelder

Lieutenant Commander
Joined
Aug 30, 2010
Messages
1,780
Re: Transom strength for hydraulic jackplate

If you want my opinion, I can't justify the price of the jack plates vs performance. Now with that said, it comes from expenerience. I've owned two boats with hydro jack plates and one with a manual plate. Transom problems were never an issue with any of them, my problem was the extra performace gained at top end was only a few mph, not worth the money to me. Now for your shallow water deal, you will benifiet there, but I too fish the shallows and just trim the outboard up and use the trolling motor. It's all a matter of "what you want". But I don't feel transom problems are a concern.
 
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