GT 160 prop suggestions

[Hyperacme]

A NFB steering system will tame the torque steering.

NFB Rack ...
http://www.seastarsolutions.com/products/mechanical-steering/nfb-rack-steering/

NFB Rotary ...
http://www.seastarsolutions.com/products/mechanical-steering/nfb-4-2-rotary-steering/

[David CVX-16]

Rakers have a lot of torque steer, but as Gregg mentioned, a NFB steering system eliminates it. 

[63g3]

Thanks for the heads up on the Raker, they look like they would behave like a Laser which I am more familiar with.  I appreciate the lead on the NFB. I have an NFB rack and pinion clutch system on a 23 Chris Craft I/O I restored, it's awful at least in my opinion.  It works by basicly locking the rotation with a sort of sprauge clutch system so you have to break it free to steer. It makes it very hard to initiate a turn of the wheel and lots of effort to over come what I'll call stiction ( half sticking half friction) to feather the wheel back and forth like you would when countering chine walk. If you just want to let go of the wheel and not have the wheel turn  it's perfect for that scenario but, in this instance that's not the issue.  I probably did not fully explain my concern.
Normally speaking torque steer is just part of the speed deal, I expect that,  it's  pretty hard to avoid with high Perf props and I can handle chine walk just fine it's just I am mindful that Glastron in 75 did not supply high Perf steering cables so I don't want to tax it pulling against torque steer where I am leaving everything as original as possible. So ideal prop is one I can trim out with no cavitation and gives at least some amount of bow lift without inducing much torque steer. I realize this will leave some speed potential on the table but that's fine.....and of course there may not be such a prop either!
 I would do a dual cable but because of originality concerns this boat will always be a single cable.
     That said I did scrounge up  a modern cable mount tube that will fit the existing transom mount swivel ball hardware and that would allow me to put a newer style, stronger cable and better helm in the boat with minimum visual impact on originality. The original Morse cable outer jacket connection to the transom tube is an obsolete style and at the motor connection end of the cable  has is a threaded stud at the end not seen on current day cables.  On the rack end it is not a width or bolt pattern used anymore so the whole thing has to go but, at least  I can leave the transom mount as is intact.
 I might do that in a year or so as an upgrade, I gotta let the wallet cool off a bit but I'm thinking it will be a straight rack and pinion rather than NFB. Maybe there is something wrong with the NFB I have and have read similar disappointing comments about this system on other sites.....or maybe they have ironed that out. I swapped it out on my CC after two seasons of what felt like arm wrestling at every turn of the wheel in idle on up. Maybe you guys have better NFB results?

[DL-North]

63,

Pretty new boat.

But that's going on with the motor?  You said it was a 4 cyl and you were switching to a 6, are you keeping the same lower or?

Dan

btw, nice car too.

[Hyperacme]

My motor was all the way down, cable non-NFB steering, prop testing.
http://forum.cgoamn.com/index.php?topic=3265.0

Try a bunch of props and see what works for you ...

My CV is far from original/stock/mint.
I lifted my motor, mounted a Lazer II 22P and installed a Baystar hyd. steering system.
54 MPH / GPS no chime walk or torque steer ...

[Retro Performance]

I wonder if a four blade prop would help meet your criteria? Not so sure it would be period correct though................Both those boats are really nice examples

[Hyperacme]

The bronze 2 blade was the best for torque steer, but it's not easy to find the performance ones Dave had ...

"Kind of forgot when/where in the order we did it but tried one of his 2 blade props ..
2 blade 22P - 50.8 mph at about 5300 -5400 rpms, very little torque steer, but weird noise, maybe vibration, maybe just the way the prop is, coming from motor, worked pretty good and felt very smooth."

Ross's prop testing ...
http://forum.cgoamn.com/index.php?topic=2371.0

[David CVX-16]

The 2-blade bronze prop was by far the best and fastest prop on my V-153 with the 115 HP Merc, hitting about 53 MPH. The prop has little bow lift, but the blades are thin and there are only 2 blades. Others have tried it, Bruce on his CV 16 and he had vibration, and Chris on his GT160 and it did not work for him. For 63g3 the safest prop to try is the Ballistic 21" pitch prop that has medium bow lift, little torque steer, and operates well with the motor not elevated, which the Laser II requires. Steve A. hits about 57 MPH on his CV-16 with a 115 HP Merc using a Rapture SS 21" pitch. I had poor luck with that prop. A Raker would require rehubbing to a Mercury 15 spline shaft.

If I ever switched to the 1988 115 HP Merc on the CVX-16, I would try a 22" Laser II first, then see if I could rehub the Rakers and SRX to fit the Mercury. 

 

[63g3]

DLNorth, I took the 1975 850 off and put on a 1976 low hour 1150 I found. Both are the lower flywheel rated motors , the 1150 does have a fresh powerhead, I've gone through it to be confident in condition.    Although the mids are the same, the lowers  have different ratios and I wanted PT so in the end it was easier to swap out complete motors.
The 850 was just to clean to break up as would have been needed to leave that mid clamped on and exchange  everything else required. 
David, Hyperacme, good idea on the earlier brass two blade. I have an eye out for one of the 2 blade bronze "hi rake" performance props as Merc named them in the day.    The standard two blade brass are not cupped so I think that makes those a non starter.  I do have a 24 pitch hi rake but I think that's too steep. ( also no where near as pretty as one posted!) I have a 24 Merc elephant ear SS two blade ( also too steep for this) which testing on other hulls showed it had some bow lift, minimal torque steer and oddly it also made the motor sound different. It was however slow compared to newer three blade designs but, if I could find either of these in lower pitches those might be the ticket.
I'm hovering around 19 or 20 pitch where this is the weaker flywheel hp 1150.  I think most of you here have the later prop rated 1150's in either OMC or Merc flavors, which really would compare to about 140 or so at flywheel so I have to pitch down from where you guys are.
I had not thought of a 4 blade interesting idea....not worried too much if prop is not vintage correct, I'll compromise on what's not really seen😉.   The 4 blades when used on inboards are like butter.
Randy

[David CVX-16]

I have had several Hi Performance Mercury Quicksilver 2-blade bronze props, 20 and 22 inch. They meant to run with the motor in an elevated position, as Mercury used them for racing. The standard 2-blade bronze prop is a better prop for you as I have tested both props against each other. You should be looking for part number 48-49630, and the prop can come cupped from the factory, as I bought one years ago at a bargain on e-bay. A prop shop could also add the cup if you cannot find a cupped prop. Used to have four of the 48-9630's, but sold them all when I sold the V-153. A fellow Glastron member bought two of them and loves them. Here are pictures of props for a Mercury - Ballistic, Quicksilver, and Powertech. 



   

[63g3]

OK good to know on the high rake brass really needing higher running height, I'll stop looking for those. The standard brass ones are easier to find and you are right on adding the cup, so that's a reasonable option.   I think a -A3 suffix might mean cupped from factory and a -A1 is non cupped but, it was a looooong time ago I was looking at those designations.
Great info guys really appreciate it.
Randy

[V153]

Rakers have a lot of torque steer, but as Gregg mentioned, a NFB steering system eliminates it.

Keep in mind an NFB system will make the wheel harder to turn.

[V153]

If I ever switched to the 1988 115 HP Merc on the CVX-16, I would try a 22" Laser II first, then see if I could rehub the Rakers and SRX to fit the Mercury.

Obviously you'd have to rehub an SRX. But Rakers have been universal hub for awhile.

Don't forget a Lightspeed if ya see one cheap. Good hole shot prop.

[Silver GT-150]

Wow, those are two VERY nice boats!  Our friends had the exact Vector with a 150 Merc when I was growing up.  There's a GT-160 with a 115hp Merc on the lake I live on now exactly like yours but of course not near the condition yours is.  Fun to see it on the lake.

[David CVX-16]

Obviously you'd have to rehub an SRX. But Rakers have been universal hub for awhile.

Don't forget a Lightspeed if ya see one cheap. Good hole shot prop.

The Raker universal hub is only on the V6 and V8 models, 14 1/2 diameter blades, called the RAKER II TBX. They do not make the universal hub for the 13 1/2 diameter V4 models. I do not know why - maybe not enough demand.

I also noticed that Laser props are made in 19,20,21,22,23,24,25,and 26 inch pitchs whereas before it was in even pitches only. I wonder if they have improved the design of the prop as the years go by. The original Laser II prop must have come out in the 1990's. 

[Hyperacme]

"I also noticed that Laser props are made in 19,20,21,22,23,24,25,and 26 inch pitchs whereas before it was in even pitches only"

I was looking on the Merc. site and saw LaserII come in new/more sizes ...
But they have only been out for a year or two and new one's are crazy expensive !
Would like to try a 23P in 10 to 15 years when price of used one's on Craigslist comes down ... LOL

[David CVX-16]

I have a feeling that the Laser II prop has fine tuned many times over by Mercury Marine in its lifetime as they make modifications and test them. Also the exactness of the castings and ways to finish them have improved. Years back, DAH prop works in Wisconsin boasted that they could always make a Laser II faster as the blade pitches were not consistent, nor the prop balanced.

Mercury Marine would never tell you the above, or tell you the bad years of the Laser II before they were improved.