Author Topic: Talk about fast CVX-s and Intimidators  (Read 1359 times)

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Talk about fast CVX-s and Intimidators
« on: June 24, 2015, 10:15:18 PM »
Tom Brown:

One thing to keep in mind about these old Carlsons is the whole lot of them are 50~60 mph boats. Perhaps the CVX-20 Sprint was built with the fastest speeds in mind as some of they were hitting mid 80s back in the day. Perhaps because of that, they are extremely exciting to make go fast. It's always exciting to do something you shouldn't be doing. My Carlson is a CVX-16 and yeah, I've had it up into the triple digits. Frankly, I think the less I talk about it the better because it's not a safe thing to do. It's the rocket powered skate board. Cool? Oh yeah. It's a devil-may-care, safety-shmafety, let's get crazy, type of a thing. The thing is, of hand full of times I've had it up to extreme speeds, something bad has happened. Nothing terrible, as witnessed by the fact I am typing this message, but something bad, all the same. Things like bow steer induced hard right turns, backing off on the throttle and having the engine pop up like it hit a tree stump because of the extreme gear case drag at those speeds (I originally ran a fishing engine mid section on a 2.5 EFI), and chine walk at frequencies so high I wouldn't have thought them possible. I literally consider myself lucky to be alive. The old Glastron hulls are built pretty well, compared to anything from the day and even contemporary boats, but they still might delaminate or have some other catastrophic failure at speed. If something like that were to go wrong, it would be a fade to black situation. When you're going really fast in a Carlson, you will understand God's message that you better stop doing what you're doing or he is going to bring you into his office for a debriefing. Is this melodrama? I have no doubt it sounds like it, however, I don't feel it is. Please be careful with these old hulls. They aren't triple digit performance hulls, although they are really cool even today. :

When the floor and stringers are that rotten, the hull will loose some of it's shape. The hull itself is quite plastic. In the same way, you can straighten it. I built a torsion box out of MDF, set the hull on it, and then put large amounts of weight on the stringer when I glassed it back in. The weight was in the form of a couple of anvils and some sandbags. That straightened things out pretty good. I only had to fill about 1/8" of hook to get the pad straight. My pad was not horizontal coming out of the mold but it was close enough. It doesn't have to be that accurate. Mine was built in Austin. I'd be more worried about the hook in the pad than making it horizontal. For best speed, knife edge the back but understand it will be very difficult to make paint stick to a knife edge. I wouldn't move the tank, particularly if you care about rough water handling. I modified the pad and inner strakes quite a bit. What I learned is that I should not have modified it. There are benefits but not significantly so. If you extend the inner strakes to the back, the extensions will be extremely difficult to get to stay on. Just look at the cracking behind the inner strakes you have now. All CVX-16 hulls are cracked there. There is a lot of flex in that region, particularly in your case with a really heavy engine and then another heavy lump of jack plate. Oh yes... 150hp e-tec. Nice engine. Good power. Pretty heavy for a CVX-16 but not the worst I've seen. I'd nix the hydraulic plate, though. Keep it light. Consider a manual RapidJack. I think the manual 6" R-J is only about 35 pounds and it's a stout piece. My handling improved noticeably when I ditched a heavy CMC plate in favor of the RapidJack 6" manual. Hydraulic steering is great. A foot throttle is a requirement. 70mph is extreme speed for a CVX-16. You'll have a hard time getting there with a 150hp e-tec ho. 60mph is easy with that power. 65mph is possible. 70mph is a stretch, to be honest. It's possible but not with a heavy boat and you don't seem at all concerned with weight. Keep it light. Don't modify the hull. Straighten the pad, sharpen the inner strakes and trailing edges a touch, and leave it at that. Nothing else matters at speed. Even the pad and inner strakes barely matter at these speeds. It's a lot of work for little gain. It's worth it if you're rebuilding a hull but just barely. For all those hours you are going to put into that hull with glass work, there are more gains to be had by simply removing the windshield. The CVX-16 is a great little hull. I still enjoy mine but I enjoyed it less when it wasn't as hard core as it is now. Once you start modifying the pad, jacking the engine to the moon, and doing all the stuff that is required to go fast, you will probably discover it's not as fun. It will be more exciting, though. They make a great ski boat. Make sure you glass in some hard points to mount a boarding ladder at back, when you rebuild it. Oh... and loose the floatation foam. It will just make you sink faster, at this point. Once it water logs, that stuff is like rock. Forget it. You don't need it.

Employee of Glastron/Carlson:

The Carlson Intimidator was a fun project. I worked at the Carlson plant on Grove Street in Anaheim from 1979-1981 and was part of the development team. We quickly learned that the Jet and Outboard bottom on the CVX 20 wasn't quite right for a stern drive application (5.7 MerCruiser/260HP w/Alpha Drive). Our prototype boat probably went to the water (Golden Avenue in Long Beach back then) nearly a dozen times. We brought along several buckets of "mud" (quick set bondo) and lots of sanding blocks. We'd run the boat, bring it back to the trailer, add or subtract some material on or off the bottom to see if we could pick-up a mile or two and make it handle better. After about a month of testing we had a really good running hull (69-70 mph on radar with 2 people in the boat). Glastron corporate in Austin was a little nervous about selling a 70mph stock boat to the general public so we had to make a couple more bottom revisions to slow it down a tad (top speed of the production version was 65 mph). The CVX 20 was an amazing boat -- at that same time we came out with the "Ski Machine" (CVX 20/outboard) that was a super tournament style boat, especially for serious slalom skiing. And of course, there were a few (2 or 3) custom/handmade CVX 20s that had a "pad" bottom and raced at the Lake Havasu Outboard Classic and the Parker Enduro -- but that's another story. The minor bottom changes to the Intimidator included adding a little hook to the bottom (the last 3 to 4 feet -- about 1/4") and just slightly reducing the depth of the two lifting strakes closest to the keel so the boat didn't ride quite as high out of the water at top speed. Basically, just wanted to increase wetted hull surface and create more drag. If you really wanted to pick-up speed on a CVX 20, modifying the vee-keel into a true running pad was the trick. Alan Miller, an employee at the Carlson plant in Anaheim did the first one. After that we built several (super lightweight) center steer, pad bottom (no mold) CVX 20s for Mod VP racing. Evinrude supported the effort with some well built/modified 235 HP V-6 engines. Well known Unlimited hydroplane racers Bill Muncey and Chip Hanauer were part of our driving team. When everything was right, these special "race" CVX 20s with a 235 Evinrude were good for about 90-91 mph

Owner of the 1981 CVX-20 "Intimidator":

It currently has a 400hp small block crate motor and runs 80. I built the boat back in the mid 90's, I found it at Catherines Landing at Lake Mojave sitting in the mud in outside storage for $800 through a friend of mine. The lower unit was blown out and the exhaust manifolds were cracked. Got it home and fixed what was needed to get it running a used it for a couple of years. then tore it completely apart to rebuild it. There was literally nothing on that boat that didn't get touched in the rebuild as well as many changes to it to get it to the point where it runs a stable 80 mph. It has been a great reliable family boat and still gets alot of looks. In my opinion you would be hard pressed to get anymore mph out of one of these unless you made a drive change to handle more HP, hydraulic steering and trim tabs. But the main key to more mph and better handling is the bottom, there crap without alot of work to them. I just wanted to make it clear that it was an original Intmidator and not a CVX as there is quite a few differences. I did do alot of glass work to it and still itch to this day from it. As my first boat project it was alot of work but worth it. The boat is starting to show it's age now as I tend to run it pretty hard but but it takes the abuse and keeps on going, all in all it's still a great family boat. When I flipped mine upside down to work on the bottom it had a hook in it, it was anywhere from 1/4" to 3/8" and in some places almost a 1/2". I fixed the hook, straigtend the lifting strakes and knife edged them, also knife edged the transom and chines and then textured the back half of the bottom to break up water adhesion. it was a hell of alot of work but it made a difference. 

Video of Another Intimidator running:

https://www.youtube.com/watch?v=qHMU-C1PmVU#t=17

More Tom Brown on his CVX16 ...

That's a lot of very specific questions about your boat. You wrote that all input is welcome and I have a CVX-16 so I'll take a shot at answering a few of them.

 When the floor and stringers are that rotten, the hull will loose some of it's shape. The hull itself is quite plastic. In the same way, you can straighten it. I built a torsion box out of MDF, set the hull on it, and then put large amounts of weight on the stringer when I glassed it back in. The weight was in the form of a couple of anvils and some sandbags. That straightened things out pretty good. I only had to fill about 1/8" of hook to get the pad straight.

 My pad was not horizontal coming out of the mold but it was close enough. It doesn't have to be that accurate. Mine was built in Austin.

 I'd be more worried about the hook in the pad than making it horizontal. For best speed, knife edge the back but understand it will be very difficult to make paint stick to a knife edge.

 I wouldn't move the tank, particularly if you care about rough water handling.

 I modified the pad and inner strakes quite a bit. What I learned is that I should not have modified it. There are benefits but not significantly so. If you extend the inner strakes to the back, the extensions will be extremely difficult to get to stay on. Just look at the cracking behind the inner strakes you have now. All CVX-16 hulls are cracked there. There is a lot of flex in that region, particularly in your case with a really heavy engine and then another heavy lump of jack plate.

 Oh yes... 150hp e-tec. Nice engine. Good power. Pretty heavy for a CVX-16 but not the worst I've seen. I'd nix the hydraulic plate, though. Keep it light. Consider a manual RapidJack. I think the manual 6" R-J is only about 35 pounds and it's a stout piece. My handling improved noticeably when I ditched a heavy CMC plate in favor of the RapidJack 6" manual.

 Hydraulic steering is great. A foot throttle is a requirement.

 70mph is extreme speed for a CVX-16. You'll have a hard time getting there with a 150hp e-tec ho. 60mph is easy with that power. 65mph is possible. 70mph is a stretch, to be honest. It's possible but not with a heavy boat and you don't seem at all concerned with weight.

 Keep it light. Don't modify the hull. Straighten the pad, sharpen the inner strakes and trailing edges a touch, and leave it at that. Nothing else matters at speed. Even the pad and inner strakes barely matter at these speeds. It's a lot of work for little gain. It's worth it if you're rebuilding a hull but just barely.
 For all those hours you are going to put into that hull with glass work, there are more gains to be had by simply removing the windshield.
 The CVX-16 is a great little hull. I still enjoy mine but I enjoyed it less when it wasn't as hard core as it is now. Once you start modifying the pad, jacking the engine to the moon, and doing all the stuff that is required to go fast, you will probably discover it's not as fun. It will be more exciting, though.
 They make a great ski boat. Make sure you glass in some hard points to mount a boarding ladder at back, when you rebuild it.
Oh... and loose the floatation foam. It will just make you sink faster, at this point. Once it water logs, that stuff is like rock. Forget it. You don't need it.


Gregg
'76 CV16