Minnesota Classic Glastron Forum
General Category => General Discussion => Topic started by: Mechanick on September 23, 2018, 10:25:15 PM
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We are mid way thru replacing rotted keel, floor and transom on a CVX 16 (Johnson GT 150). Drove over to Evinrude’s demo on Lake Minnetonka this weekend and very suprised to see a lot of 6”+ static jack plates being utilized with outboards for more “efficiency and better handling.” Commentary on the web seems to favor full flotation set-back brackets (vs jack plates) to get the same efficiency effect as a jackplate but added flotation when sitting in the water to compensate for greater leverage the weight of the OB has sitting back further. Is this something anyone in this forum has considered or implemented on a boat as small as the CVX16? Is it more hype than the effort required? Feels to me like setting an OB back an additional 18” on a short boat would add stability. We mostly straight-line ski and barefoot, and a longer “wheelbase” (if you’ll permit that comparison) would seem a good thing, no? Advice much appreciated!
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Maybe check over at Scream & Fly …
I've seen OB bracket like that on vary large off shore fishing boats.
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No. You don't wanna put one of those on a CVX16 ...
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No. You don't wanna put one of those on a CVX16 ...
. “No” to the bracket or jackplate or both? Maybe 18” is a stretch for a 16’ boat. I see 3” setback via jackplate on youtube CVX16—looks dialed in!
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Jack plates are to get the motor lifted up and get as much of it as possible out of the water for speed.
If your skiing with your CVX, your going to want to keep motor down, or you'll get blow outs in corners.
Aren't speed for skiing around 30 to 35 MPH ?
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Thanks...Good point on cornering. We mostly straight run our skiing (only sharp corner to pick up a dropped skiier ;). Barefooting gets us into the 40-45 range, and weve had issues getting a 16 foot boat to that speed with an older 150HP in the past, but it is really improved stability from a setback that we are after here. Static jack plate or bracket—just asking if more setback adds stability and how much setback is ideal.
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Maybe check over at Scream & Fly …
I've seen OB bracket like that on vary large off shore fishing boats.
. This site helped, thanks!
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WOW !
A Johnson GT150 didn't have enough power … What prop are you running ?
Sorry .. I don't know the answer to your question about stability.
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OK, dare I say it, you need a Ski Machine. Somehow 16 foot boat, 150hp, and barefoot skiing at 45mph tells me I've become my parents. Honestly, if a 150 wont push a 16 at 50mph plus, there is something wrong.
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OK, dare I say it, you need a Ski Machine. Somehow 16 foot boat, 150hp, and barefoot skiing at 45mph tells me I've become my parents. Honestly, if a 150 wont push a 16 at 50mph plus, there is something wrong.
That's a great idea!
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LOL—gorgeous boat! I think my transom will look that big if I would build it like I wanted ;). Ok, to be fair, it was a 16’ Larson tri-hull with the 150 (Prop must have been a 18+ pitch?...too young at the time to notice) but with 5 people on board it struggled to pull a 180# barefooter. I know this CVX16 is a whole lot lighter, so shouldnt be an issue for getting to speed—why I’m asking is if adding setback create more stability. ((Whats the transom set up look like on that Ski Machine?)
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Ski Machines & Sprints
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Few more ...
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Sprint
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Ahhhh! I bought the wrong boat! ;). That is a great looking ski set up—I really like that stretched tail and what looks to be a much sturdier transom. Thanks for the pics! I’ll have to put one of these on my to do list.
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This one is worth about $1000 to $1500 from look's of pictures.
1982 GLASTRON SKI BOAT (Glastron Carlson) - $3500 (Roseville)
https://minneapolis.craigslist.org/ram/boa/d/1982-glastron-ski-boat/6701797650.html
A hard to find classis ski boat. Glastron CVX-20 with a nice Evenrude 150hp (rated 200) will do over 50mph and water ready now. Interior seats and padding was replaced several years back and now just needs some new wood bottoms that we already cut. You can still enjoy the rest of Summer and fix seats this Winter. Solid trailor and newer custom cover. ( if we make a deal I can throw in life jackets tow rope and anchor) $3500 OBOffer
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I think you are spot on with your $ assessment—gelcoat in that poor a shape usually comes with a soft floor/keel. Here’s my Craigslist purchase...before and after teardown. Will send photos after transom is beefed up and glassed in.
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The interesting thing about this is that the new Glastron OB's have a setback pod on them now. Clears up the splashwell, so you don't need to have one, and allows a full swimdeck area. Honestly, a great design. I'm curious how they'll hold up in 20 years, but they don't have to care about that...
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. “No” to the bracket or jackplate or both? Maybe 18” is a stretch for a 16’ boat. I see 3” setback via jackplate on youtube CVX16—looks dialed in!
No to the bracket. Jack plates are fine. 6" Atlas on a CVX16. 150 HO Etec:
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Fwiw if your primary use is for pulling skiers/toys? I'd think you'd want the motor on the transom, prop buried deep. Imo.
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Doug runs the jack plates solely to save the Manatees. Even if it saves just one, its worth the money. Just ask him.
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Doug runs the jack plates solely to save the Manatees. Even if it saves just one, its worth the money. Just ask him.
Love em so much I just made another donation. $230 bucks. (Second offense ...)
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" Fwiw if your primary use is for pulling skiers/toys? I'd think you'd want the motor on the transom, prop buried deep. Imo. "
That's my thinking …
It's not a heavy boat and has a pad, thinking more LU in the water the better.
Maybe ...
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Well what it all boils down to is do ya wanna tow chit, or go fast. Try as you might, there is no happy medium.
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You can get a few more MPH out of it by changing props.
There's a guy on FB that picked up 10 MPH by going up from a 21P to a 22P prop … :o
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Great looking set up and color! Thanks for the clarification.
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Fwiw if your primary use is for pulling skiers/toys? I'd think you'd want the motor on the transom, prop buried deep. Imo.
Agreed—-the idea was greater stability from the setback of a jackplate, not really speed from tweaking the motor up with the jackplate.
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When you say "stability" .. Do you mean ability to track straight when a skier is cutting across and pulling on boat from an angle ?
CVX16's have pad's so there's not as much hull in the water as say a V hull, there designed more for speed then pulling skiers.
There also fairly light at 700 lbs. for just the boat, so under 1500 lbs. with you and fuel, battery, etc.
Repair hull and mount motor .. See how well it works ..
You can always add the jack plate later, bolt hole are the same as your motor, although your steering set up might have to be modified.
I would think a 150 HP motor and the right prop should work OK.
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Thanks—good point I can add a jackplate later—I can still beef up my transom/knees to handle either way on the rebuild. Wanted to figure out early if I had to make other mods now (eg steering) in prep for a setback. But clearly my 18” setback idea is OUT...so thank you to everyone for the input. Ha ha...I would have hated to have shown up at the next summer CGOAMN get together with an 18” setback to the derision of all ;). (Im betting my 6” jackplate will slide thru unnoticed.)
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Yep .. Beef up transom no matter what you decided to do !
I went from G/C design of two, half inch boards nailed together .. to two three quarter inch boards with 1808 FG sandwiched between them. CVX design already has knee's but you could "beef" them up also.
Or even go with the poured composite transom.
Something to think about now is what are you going to use for a steering system ?
If you go NFB, your going to have to make some adjustments for cable routing if you get a JP.
Your with in HP limits of a Baystar, which would make set up and changes to set up much easier ..
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Have not had to much experience with a jack plate. A good fried of mine had a fixed jack plate on a GT 150. Approx 6 in set back and height was fine tuned until it was just right. Was not involved with the tuning process just was able to drive it a few times. Motor was a Yamaha 90. It would go 55mph with no experience of chine walk. Very stable at that speed. Out of the hole it was full trim down hit the hammer and hold up trim until it quit and you were gone.
When doing something like that hydraulic steering would be the way to go because with a cable steer you would have to come out the back of the boat to make a nice radius of the steering cable. That's what he did.
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Tom, from the Twin Cities, whom I have met twice on the rivers, has a CVX16 with a 115 HP with jackplate used for top speed in which he tries to elevate the motor as high as possible off the transom. Runs 22" and 24" Laser II props hitting about 60 mph. I would think that a jackplate is for higher top speeds, adding stability by positioning the motor further from the boat, acting as leverage
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I think it was Jerry that once commented that a JP would place the motor deeper in the water from the boats running surface compared to a motor on transom. Of course the JP would have more range of adjustment, to lift higher.
Like everything to do with set up, Ya never know how well it will work until ya try it …
Wondering about "Your" history of your CVX ?
Have you run it yet with the motor you have ?
What year is your motor ?
There's a "Fudge Factor" with boats and motors, a dealer can install a motor that's 15 % larger then rated cap. of Mfg.
But your 150 HP couldn't have been installed by a dealer, so must have been mounted at a later date.
Motor Mfg. also use the "Fudge Factor" on motors, Evinrude makes a 115 HP motor and a 115 HO motor, which would have about 15 % more HP then the regular motor. Merc also makes a XS with higher HP then there regular motor.
Your Johnson GT150 would be one of the higher HP motors, maybe closer to a 175 HP motor, if it's in good shape and running well.
I would guess even with your motor on transom and a prop that would pull skiers .. You would still be able to get mid 50's MPH / GPS.
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I would guess even with your motor on transom and a prop that would pull skiers .. You would still be able to get mid 50's MPH / GPS.
I'd think it'd run a lil better'n that.
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To put it into perspective. Once yer goin fast? It takes alotta HP to make ya go a whole lot faster.
If'n yer just gonna drag chit? That's a different story.
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Just to follow up and close this one out: So I went with the general advice and just direct mounted the motor—a GT 150. Without a jack plate to adjust I mounted it high (cav plate about 1” below trailing edge) and result was it constantly cavitated. So before trying any adjustments I added a $60 ‘whale tail’ to see if i could keep it high without cavitating—that did it. The 150 is an old motor (just over 100lb compression on all cyl) but she just flies now with superb handling (my first Carlson). Snaps out of the whole too with tons of acceleration. Next motor will be a newer 125/135 but as long as the old Johnson keeps running I’ll keep it on the boat. Thanks to all for advice!
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One thing to add: when rebuilding the keel and floor I switched the transverse 12(?) gal gas tank to a 20 gal and mounted it inline (with the keel) and as far forward into the nose as possible—so I’m assuming that might also be a factor in why the boat pops up so flat out of the hole.
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Should have been a 20 gal. tank, unless someone replaced it.
Crappy picture .. but it sat front to back originally.
Any pictures of boat and rebuild ?
We love pictures !
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You bet....
2 pics of tank before/after. You’re pic looks like the same tank as my original...that’s a 20 gal?! Will take your word for it—maybe memory is poor on that one—I know the new one is 25 spun 90 degrees...more centered and further forward.
2 pics of rebuilt keel, transom and floor using Koosa board... but had purchased 3/8” thick for flooring—too flexible even for that narrow span so added in cross-members—worked out well.
2 pics of new seating—went with deep bench to make it super comfy and got a bit (too?) carried away with a 70’s “stars and stripes” seat covering (...I blame my dear old mum who helped me plan the sewing bit—we laughed thru the whole thing—priceless memory)...
1 pic of finished boat....man does it MOVE! I grew up with speedboats...this one is a beauty for handling and speed —takes a turn like a race-car ;)
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OK .. I'm sorry it would have been a 18 gal. tank ..
Maybe early CVX's had tanks mounted like late CV16's.
Any CVX16 owner know ?
Picture is my tank (18 gal.) in CV16.
Your CVX looks GREAT !
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Yes—-transverse 18 gal was what it was. So thats a CV config? Ok. So it seemed too small and way too high for what i needed to do with the boat so I went to 24 gal, spun it inline, dropped it to the floor and shoved it forward (the new one had a v shaped base which let me slide it further up into the nose).
This gas tank configuration also ended up offering a lot more leg-stretch room and storage.
Thanks again for all your input as I went thru this project—much appreciated.
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What year is your CVX ?
Yes .. Seems like a weird set up.
The CV16SS had same set up with a ski locker in center console.
Picture is Jason's CV with replaced plastic 18 gal. tank.
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Title says its a ‘78. I had the same wooden platform you show in your picture, but no cutout for ski storage. So lots of inaccessible (‘wasted’) space up front and no legroom. While the new configuration was mainly to insure the bow stays low out of the hole, the extra legroom ended up being a even bigger plus. I found a pic that (sort of) shows mid-project where the tank sits relative to the dash and front seat—-you can see the back of the aluminum tank about 8” forward of the dash, about 24” wide.
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I’ve highlighted in yellow the marks from the original (transverse) tank mount. You can see the new mount, even though inline and a much bigger tank, actually comes to the same point leg-room wise (but of course now on either side you are “free and clear” all the way to the nose—lots of room to stuff life jackets and still stretch the legs. I had intended to mount it right on the floor, but by trestle-ing it up a few inches it let me slide it further forward 6-8” (and still leave a healthy gap from the hull itself.) To facilitate storage I built 2” thick foam “walls” on either side of the tank, “floor to ceiling” and all the way to the front, so no chance of gouging the aluminum tank with an errant ski or letting anything stored fall under or behind the tank itself.
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If you look on the right side of stern, just below rub rail, there's a HIN.
Last three or four digits are year and month built.
If you care to share the entire HIN, I'll add it to our list.
Sometime titles can list year boat is sold or title was lost and someone just guessed on year.
Your tank set up looks great !
Were you able to keep original gas filler on deck or did you have to move it to fit new tank location ?
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Original gas filler actually worked fine. Boat is in storage—will get that HIN# over to you in May. Hoping to make it to the rally this year!
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Your local ?
Great hope ya can make it to the meet ..