Glasstron/carlson cvx 20 (jack plate)

[eracer]

Can any body tell me what to expect when adding a jack plate on this hull? What would be better 6 8 or 10in.
I am currently running a 84 235 Johnson. Its fresh and runs real strong for an old cross flow, top speed of 68 with 4 (me the wife and 2 100lb kids) about 72 if the water is right by my self, There is more but i cant handle the chine and the tork steer. Prop is a 13.25x25 shooter. When running it hard like that i wind up using a lot of positive trim, heading into a little bit of chop you can feel the hull come out and thats when it will get good top end. I want to find a 225 looper to have ready at the same time i install the jack. I have no experiance with a jack set up. I use the boat for sking and a ocasional blast across the lake. Would a manual plate have a happy medium? Does any thing need to be done to the transom to beef it up?
You guys's help would be appreciated.
Eracer

[tombrown]

I run a CVX-16 and just put a 5.5" CMC manual jack plate on it. Boy, did it improve the handling of the boat. You wouldn't believe it. What's odd is that I thought the handling was great before.

The Glastrons seem to have weak transoms. How is your transom built? Mine is two thickness of 3/4" plywood encased in glass. If you're nut super careful about keeping the transom sealed, they go soft really fast. When I pulled my 1500 off, I was shocked and extremely disheartened to find that one of the engine mounting holes had soft material around it.

I built a transom bracing system that I think is pretty good. I'll get some more pictures of it this weekend and send them to you, if you like. My system is a wee bit different because the CVX doesn't lend itself well to sending rods straight forward through the splash well. I've seen this done and I'm sure it helps, but my system bolts to the center stringer and I think is at least as strong.

By the way, I'm running an XR-4 on my CVX-16. The transom is holding up beautifully. Unfortunately, there are some hairline cracks starting to form on the keel right in front of the transom. :( If I end up having to flip the hull to fix the cracks, I'll pull the transom out too and pour in a new one with Sea Foam. That way, I'll be able to mould in knees and the center stringer at the same time.

To answer your question, I'd probably go with a manual jack and set of spacers to get into the 8 inch range. I've seen CMC ML-65 plates sell quite cheaply on this board. That will give you 5.5 inches of setback and there are 2.5 inch spacers available (CMC - 65213) that will give you 8 inches in total.


Good luck,

Tom Brown

[tombrown]

I can't comment on the speed improvement. Before, I was running a 1500 with no jack plate. Then I switched to a jack plate and an XR-4. Given how a couple of clicks on the up trim and it loosens up and breaks free of the water, it has to be faster than no jack plate.

Even without the speed improvement though, it was very, very worth it. The ML-65 doesn't cost much used. The biggest problem you'll have is with your steering. The jack plate will force you to change the cable routing.


Good luck,

Tom Brown

[tombrown]

There's a terrific group of guys over at the Classic Glastron Owner's Association. It's mostly made up of people who have used Glastrons and just want to keep them going without spending too much money. Right here is the place to be for anything engine or performance related, but it's a great bunch of guys over at CGOA and they've got the original brochures scanned in for almost every year and model as well as a bunch of racing history and even some notes from Art Carlson and Tom Gaston. They're working on putting some original Glastron service information into PDF form. I think it's pretty interesting for Glastron owners.

http://www.classicglastron.com/

[eracer]

Tom;
Thanks very much for the info on the set up and the glasstrons.
I would like very much to recieve any thing you got on them.
In reguards to the transom,
mine developed cracks in the glass on top of the tronsom in the corners. I re glassed it in and found the problem was in the trailer. Moved the bunk rails way to the outside and all my problems went away. I use a special plate i made that goes across the top and down in to the well. I have carfully watched the transom under loads and its doing great. I did this about 8 years ago. What is your thoughts on using a stainless plate on the back, with the jack plate over it?? Is this somthing that people do? Ive read some interesting things on this board. Im like you if it breaks or goes bad i will open it up and make it twice as good. I like the boat alot guess thats why ive had it 11 years.
Thanks again, Kent

[eracer]

Tom ;
Just one more thing, my steering all needs to be replaced your thoughts on that as well please.

[AlaskaStreamin]

My dad has a '72 CVX 19. It started as a jetboat, but after several blown 454's, he went to an outboard. We glassed in the holes and hung a '78 200 Evinrude on the back. After several years, we added a 14" set-back and a $500.00 '89 225 Yamaha. The added set-back really helped lift the boat. These boats are no flyweights and need a little help from the set-back. Good luck!!

[tombrown]

I'll send you my transom brace stiffener pictures sometime mid week. Later this afternoon, I'll be heading out to the lake and I'll get a bunch more pictures then. I'll try to get some pictures of the steering modifications too. When I put the jack plate on, I had to re-route the steering cables out the stern.

I wouldn't use a stainless plate. It will have a galvanic reaction with the aluminum in the jackplate and engine. If you use a stainless plate, insulate it from the jack plate with a layer of teflon. Why not use aluminum?

The idea of using a plate between the transom and the jack is a good one. It isn't unheard of that a transom will break at the bottom of the engine transom clamp. A plate would spread the load out although I think a jack plate will do some of this too. I decided not to do this for two reasons. First, the jack plate has a lot more surface area touching the transom than the engine clamp. Second, the way I've designed my transom stiffener, it also helps distribute this force.

I love my CVX, too. It was clear before I went whacko on it that it wasn't worth it from a cost point of view.

As far as steering goes, I went with the Teleflex NFB Pro dual cable system. It seems to be the most common system being run. The Mercury Ride Guide system is probably better, but I don't have any first hand information to back that up. I went for the NFB system because I wanted to tame the torque steer and I didn't want to run a cable down each gunnel. The main advantage of the Mercury system (from what I can tell) is that you can run a cable down each side of the boat and then one cable is always pulling on the engine. That's all well and good, but I had to carve up the back of my boat a bit to re-route the steering. I didn't want a cable in the way of my boarding ladder. So far, the NFB system has been absolutely beautiful. Now I have no torque steer whatever. I can let anyone drive the boat and it steers like a car. It's a real treat.

Ron's story is really interesting. I'm kind of blown away that they could hang a heavy Yamaha on the end of 14 inches of setback. They must have really done their home work with regards to building the transom on that CV-19ss when they turned it into a CV-19. Ron, can you give us some insight into what you guys did?

One thing though, the transom on a CV is quite different from the transom on a CVX. I think the CV transom goes the complete width of the boat whereas the transom on our CVX hulls only goes a little wider than the splash well. I don't know what the means as far as strength, but I've been told that the Glastron transom is not as strong as Hydrostream or Allison. I think it's true because I've seen a lot of overpowered CVX hulls and the transom usually pulls away from the side pods at the back.


If you want to see the CV-19ss:

http://www.classicglastron.com/72gl-carlson-index-web.html


Keep in touch and don't hesitate to drop by the CGOA, register your hull and hang out on the board. You might be disappointed at the technical knowledge base relative to here, but they know their Glastron hulls and history. Also, I've started a Glastron performance table where we can put our performance data. You might find it interesting:

http://tombrown.100megsfree3.com/boating/Performance/Performance.html


Regards,

Tom Brown

[AlaskaStreamin]

You're right on the CV vs CVX. I thought my dad had the CVX but it must be a CV. The transom changes angles and sweeps back on either side of the motor. We made our own bracket out of 3/8" aluminum plate. I'll get some pictures and send to you. This boat doesn't have a motor well. It has a solid deck like a sun deck that ties the transom to the sides of the boat. We also added knee braces from the inside of the bracket to the stringers.

[eracer]

Special thanks for you guys's responces,
hope to learn lots more.
Kent

[fyremanbil]

Hope I'm not to late, but I just read your thread. My dad had a CVX 20 in the early 80s and your description brought back memories. Yes, our transom cracked! Dad built aluminum plates for both sides of the transom. BIG plates. He added a jack plate, but I dont remember the specs. I DO remember the chine walk. Could get downright violent at 70 mph (speedometer). He added 1 foot square aluminum ride plates to the back of the hull down near the bottom of the V. Really helped the handling at speed. I really liked that boat. It took care of this kid. I jumped that thing over the wakes of large boats (ships?) like the Dukes of Hazard. Good luck with yours (and hope you didnt get stuck with the ol flyin CVX).