Looking for suggestions

[EdwardNigma]

I'm in the process of buying a 1978 Glastron/Carlson CVX20 Sprint with a 1978 175hp Johnson. The current owner says he has a 24" pitch vented SS prop on it. He hasn't mentioned the diameter and I haven't see the prop with my own eyes yet so I can't guestimate. This seems like a bit too much pitch for this motor, especially for water skiing. I'm also unfamiliar with venting a prop and what this is supposed to accomplish. Can anyone shed some light on this for me?

 

[Dhadley]

Re: Looking for suggestions

A 24" prop is a stretch on a CVX but it could be. Especially if its a Raker and there's a jackplate involved. I have doubts about the jackplate but someone could put a 24 Raker on there and probably get rpm's in the low 5000 range. The 24 has great lift. But its not a good skiing set up I'd bet.<br /><br />Its probably a 14 1/4 to 14 1/2" diameter, depending on what prop it really is.<br /><br />Vents help you get going (holeshot). Most props have them these days.

 

[EdwardNigma]

Re: Looking for suggestions

There's definitely no jackplate on it. The owner didn't mention anything about a Raker or similar. He made it sound like it might be an OE stainless prop. What would you suggest as a better setup?<br /><br /> One other thing I'm concerned about is potential damage to the motor from underwater strikes. Some of the areas I'm likely to operate in are prone to submerged floating logs or are shallow and somewhat rocky around the boat launch/dock. I've often heard that SS props are less forgiving than aluminum models and this more likely to damage the motor. Is there much truth to this?

 

[Dhadley]

Re: Looking for suggestions

A Raker is/was a BRP/OMC prop. Get the boat running as is to establish a baseline. Then lets run the numbers and see where we can make improvements.<br /><br />A ss prop is not anymore likely to damage the motor than any other prop. The rubber hub is designed to breakaway at the same given point on a ss or aluminum.

 

[paulie0735]

Re: Looking for suggestions

I run a 20" 4 blade with no vents on my 2001 175 Johnson, its fitted to a purpose built 19' ski boat and it rips me, (200lb) up on a slalom ski with 4 adults on board and all the gear effortlessly. The 20” is too small to run at WOT. The engine will pull a 23” Raker to 5200 rpm but is hopeless out of the hole and will only pull a light adult or child up on one ski. Run the boat and see, but I think you will find that the 24 will be to big even with the vents unless you only weigh 100lb wet! Good luck.

 

[walleyehed]

Re: Looking for suggestions

I run a 20" 4 blade with no vents on my 2001 175 Johnson

The 20” is too small to run at WOT. The engine will pull a 23” Raker to 5200 rpm

If you're pulling a 23 Raker at 5200,(there is no such thing as a 23P Raker) which is severely lugging the engine, I doubt the 20P 4-blade is even running the correct RPM.

 

[paulie0735]

Re: Looking for suggestions

Thanks walleyhed, Just went and checked and yep the 23 is a 24!! <br /><br />5200 is lugging it and that was my point!! We ran it for a season because that’s what was on it when I bought the boat and I could not afford a new prop at the time. <br /><br />If anything the 20 is too small but it’s great at getting me out of the water without putting undue strain on my (getting) old joints.<br /><br />What is the correct size than??

 

[Dhadley]

Re: Looking for suggestions

Walleyehed -- wanna bet both rigs could swing a 24 Raker with a jackplate? And yes, I realize the CVX has a crossflow.........<br /><br />Oh heres an idea -- a jackplate and a TXP...

 

[walleyehed]

Re: Looking for suggestions

Bingo!<br />I happen to know where a very Fast TXP is, that would fit either rig....you boys wanna play with a jackplate???

 

[paulie0735]

Re: Looking for suggestions

In a word, YES! I have been toying with the idea of a jack plate for a while now but not to lift the engine so I can swing a big prop but to actually get it lower in the water so I can maintain bite through turns when it’s trimmed out, let me explain that last comment. My (adult) boys are into wakeboards now and trimming the engine out at low speed gives them the wake they want but causes me all sorts of grief trying to keep it planning and running at a steady speed, cavitation through bends is a problem also which just makes the problem relating to holding a steady speed that much worse. So, my theory is a jack plate may let me lower the engine for that purpose and raise it again for a nice flat barefoot wake. <br /><br />How is my theory holding up so far with you walleyehed?

 

[walleyehed]

Re: Looking for suggestions

Well, to be honest, I think you would have better luck with a higher tech prop....<br />A prop that will Plane at a slower speed and hold it, is not going to be the prop that performs best other-wise. It's hard to set up a boat to provide the most wake and hold that speed...it's on the edge of falling off plane all the time, especially with it trimmed out.<br />They make weight sacks for the aft end of the boat to help create a larger wake at the speeds you need for boarding....for what you are wanting to do, a set of smart-tabs may be the best solution, then you don't have to trim out and you can run the prop that suits the top-end best, and the jackplate will allow the use of the higher technology prop. At the speeds you're going with a board, putting the engine down isn't going to change anything....it's venting because it won't lift anymore, not because it's surfacing...

 

[paulie0735]

Re: Looking for suggestions

Thanks Kenny I appreciate your advise, I do understand what your saying about the lack of lift, but the shape of the hull at the rear actually makes a bit of a 'hole' in the water as we turn through bends at boarding speed and that together with the engine almost at full trim results in the prop turning in very aerated water. <br />Q. I’m assuming this is the reason it’s slipping?<br /><br />I’m running a quicksilver four blade as a trial 4 blade prop and while it’s a cheap prop it does hang on longer than the 21 stainless 3 blade that I was running and is great for getting me up and out of the water quickly, it also offers good midrange ‘feel’ for bare footing. I would be very happy to run a higher tech prop with a jack plate for skiing and bare footing and install the ‘smart-tabs’ for boarding. <br />Q. Will the larger ‘high tech’ prop still get me out of the hole ok? <br />Q. Would the set-back of the plate help get the prop in some better water?<br /><br />You talk about High tech props and knowing what I use my boat for.<br />Q. What would you recommend?

 

[walleyehed]

Re: Looking for suggestions

You talk about High tech props and knowing what I use my boat for.<br />Q. What would you recommend? <br />

Turbo 2+2 TH...<br />

Q. I’m assuming this is the reason it’s slipping?<br />

When the boat rolls to one side, the chine becomes a wider surface and causes motor lift and increased motor angle, so yes, this could cause ventilation...this is also where a better prop will help.<br />

Q. Will the larger ‘high tech’ prop still get me out of the hole ok?

Yes, if we're set up for the proper top-end RPM... <br />

Q. Would the set-back of the plate help get the prop in some better water?<br />

Yes, the Jackplate can help in more than one way, and usually increases ease of handling and speed. It can help with hole-shot too.<br />I would also like to ask Dhadley of his opinion on this too.

 

[paulie0735]

Re: Looking for suggestions

Looks like I high jacked your post Ed, but I'm sure you’re getting as much from this as I am. <br /><br />Ok so Thurbo 2+2 TH it is. Now just gotta get the size right, I'm guessing 23 but I'm a little concerned about loosing that bottom end pull that I have come to enjoy with the 20" Alloy quicksilver, but I'm happy to accept your advise, unfortunately there is not much of that available to us here downunder, most retailers will tell us that a props a prop, the size is different but the rest is cosmetic!! So as you can guess it’s not a science that anybody is prepared to share down here yet!<br />Are the Turbos vented or is this feature unnecessary?<br /><br /><br />Light weight 19’<br />175hp<br />Smart Tabs<br />Hydraulic jack plate<br />Turbo prop!!<br /><br />Wow, even the cook is getting excited, shame we don’t have Bass fishing down here!! I'll be over there in March and looks like I'll be coming back a little heavy!!

 

[paulie0735]

Re: Looking for suggestions

Well I had a look for a 23 but yep!!!!! Not listed, so I guess it’s a 22 or 24 but 24 does worry me, just can't see it having the 'getupandgone' that I need!

 

[walleyehed]

Re: Looking for suggestions

I want to see if I can get Dhadley to take a look at this thread....If you have been turning a 24, 3-bld at 5200, that would be about the same as a 23 in 4-blade,.....let me check first, but 800RPM even with a jackplate to get to 6000, we may have to go with a 22P in a 2+2...hang tight...

 

[Dhadley]

Re: Looking for suggestions

I've been watching and it seems to me we're trying to get the boat to do two things. 1- create a good wake at slower speeds for the kneeboards. And 2- come up with a prop for the times we want to run faster and less wake for bare footing.<br /><br />I'm thinking (out loud) that maybe a hydraulic jackplate may help. Drop it down for the optimum wake and up for more speed. I'm also gonna throw out the idea of a couple of props too. Sounds like you have a couple now. <br /><br />I wish you were here in the states. We have some testing props but the freight there (and back) would kill us.<br /><br />Anyway, I have been thinking about the hydraulic jackplate from the versatility angle. What do you guys think?

 

[walleyehed]

Re: Looking for suggestions

Personally, after running WITH one....I don't think I would ever be happy without.<br />I figured it would take a jackplate to have any chance of doing both, and I'm thinking this may be a double prop situation, maybe not...

 

[imported_bjs]

Re: Looking for suggestions

is it possible for a jackplate to make hole shot a little slower? can you run the same prop you had w\o jackplate or do you have to maybe change props? another dumb question about the 3 holes in the prop do i need to buy another prop with the holes or dont worry about them its hard to find a prop with holes for my application.what do the holes really do.hope im not asking to many questions.

 

[paulie0735]

Re: Looking for suggestions

Well, at this time I have 3 props, the 24 Raker, a 21 stainless (no brand, but numbers are 389923 14¼ x21) and the 20 quicksilver 4 blade. The 21 stainless is fine for skiing but slips badly at boarding speed. The 24 is to slow out of the hole. Switching props would mean this would happen a dozen or so times through the day, a little tedious to say the least. Typically we can survive with the quicksilver as it does hang on fairly well for boarding and is very nice to ski and bare foot with. So I'm smiling at the thought of the Turbo and a jack plate. A 22 might work if the smart tabs can bring the bow down faster, thus getting me out of the water quickly. If so than the 22 may be ok for skiing and should be better than the quicksilver for boarding. If all this holds water with you guys than I'm still smiling at the prospect of making a good thing great! Q. Does the Turbo prop come with vents, if not can it be modified to add them?<br /><br />So which plate is the next question, seems there are a few to choose from and I would only consider a hydraulic set up. My engine is already at its lowest possible height as the mounting casting is already sitting on the top of the transom and I have hydraulic steering and its hardware would necessitate a set back of around 9 inches before I can get the engine any lower, I guess the other option is to fit a longer leg (and I have thought about that option also) <br /><br />If fair to say that so far all that we have discussed I have had in the back of my mind for a while, problem is the hit and miss of ‘experimentation’ can be very expensive and has always just kept it in my head! With the help from this forum I’m hoping to avoid a lot of the misses and achieve more hits.<br /><br />Thanks to all who have so far contributed.