Prop walking F hydro

Intlwaters

Help Support Intlwaters:

Bill Eilers

Well-Known Member
Supporting Member
Joined
Mar 15, 2022
Messages
194
Ain't that something. This is one of my designs. The first rendition I built for someone, 5" tub gas. He won races with it.. this one is narrowed up for a 91 cmb. To be honest with you the boat has no issues, it's a bit light on the water at. speed. Added a bit more neg on the front spon need to bring the rest of the boat back into trim after the change in front. And it's ready for another test run. I knew this topic would open a can of worms. Helps me to understand what others are thinking and where many of the problems come from
 

Bill Eilers

Well-Known Member
Supporting Member
Joined
Mar 15, 2022
Messages
194
Well it got wet today. Hand launch twice. Pulls itself up and on plane before bouey one.. prop stock 1667 pipe at 11 1/2 head at .018.. now how can I get some eng speed. Or use that cmb as a tractor? I'm used to 45 and short pipe 67 engine speeds.
 

Attachments

  • 20221002_181706.jpg
    20221002_181706.jpg
    2 MB · Views: 0

shoboat

Well-Known Member
Joined
Jun 23, 2002
Messages
7,208
Bill,

I would put an ABC 2717-19*-38% propeller on it and take it back out and see how it runs with that on the back of it.
If it is still not enough prop I would run a 2619-19*-38% on it
next. If you still need more speed try a 2719-19*-38%. Those
three will be enough for you I bet.

Thanks,

Mark Sholund
 

bermudadude

Well-Known Member
Joined
Feb 3, 2003
Messages
256
.018" ?? its cmb right?
not gonna pull much prop with that. i wouldnt even run that much clearance on a big gas engine .

unless ur using like 25%
squish effect doesnt start happening till u go to the .010 neighborhood . tho idk what else is going on inside ur engine so take this with a grain of salt
 

Bill Eilers

Well-Known Member
Supporting Member
Joined
Mar 15, 2022
Messages
194
Thanks. Motor is new. Yes it's a cmb 91rs. Stu doesn't run 91's. So he said to set at 18 and go from there. I will tighten it up a bit. And I shortened the pipe to an adjustment range of 11to 11 1/4 (set it from 11 1/2 to 11 ") it's still rich.
 

Bill Eilers

Well-Known Member
Supporting Member
Joined
Mar 15, 2022
Messages
194
Tom I think it's worth more than 2 cents. Along with you and others, those numbers (pitch and pipe length) keep coming up.. The head space, figured it was a bit much. 50% 18% 3% of it is caster
 

shoboat

Well-Known Member
Joined
Jun 23, 2002
Messages
7,208
Bill,

If you would like I will trade you a 2717 or 2719 for that 2721?
I think that is a little STOUT to start out with. A 2.1 pitch
ratio with 5.67” of average pitch is a little to much to start
breaking in that new engine. Mine will be race ready if you
would like?

Thanks,

Mark Sholund
 

Danny King

Well-Known Member
Joined
Nov 26, 2012
Messages
2,041
Mark’s suggestions are spot on. He helps prop as many boaters as anyone does. So he has a great general idea of what works.
One thing with the abc 19 38 series is…..the 2717 is usually viewed as small. Yet it is actually more prop then Most ever ran when running octura props. A 2717 can run 90mph plus or minus a few with a perfectly set up boat. But is also easy enough to run on a boat that isn’t set perfect. All the Info is already in this thread.
Head clearance .012-.014”
Pipe 11.25-11.5”
Then make the boat right. You will learn much more from A slower but running boat and will be a lot more fun than a critical plug blowing boat.
The answers are at the lake not the internet.
 

Bill Eilers

Well-Known Member
Supporting Member
Joined
Mar 15, 2022
Messages
194
Bill,

If you would like I will trade you a 2717 or 2719 for that 2721?
I think that is a little STOUT to start out with. A 2.1 pitch
ratio with 5.67” of average pitch is a little to much to start
breaking in that new engine. Mine will be race ready if you
would like?

Thanks,

Mark Sholund
Mark cant tell you how good it Is to get your input. Little info first about the boat. version one pulled a stock 1967 but that big paddle wheel would pull transom at launch and if u had to slow and get back into it during turn. U know exactly what I'm looking for.(a prop that motor will pull.. And tune pipe and needle around that prop) that ABC I have Walt sent me when...I asked him to approximate a. 1967. My set ups.. Boat design needs lift.can adj rear and fr angles. But I like the tub to ride natural. I'll trade for what u think it needs plus a few extra for your time and effort..
Thank you.
.
 

Bill Eilers

Well-Known Member
Supporting Member
Joined
Mar 15, 2022
Messages
194
Mark cant tell you how good it Is to get your input. Little info first about the boat. version one pulled a stock 1967 but that big paddle wheel would pull transom at launch and if u had to slow and get back into it during turn. U know exactly what I'm looking for.(a prop that motor will pull.. And tune pipe and needle around that prop) that ABC I have Walt sent me when...I asked him to approximate a. 1967. My set ups.. Boat design needs lift.can adj rear and fr angles. But I like the tub to ride natural. I'll trade for what u think it needs plus a few extra for your time and effort..
Thank you.
.
A lot of work is done to that prop. Nothing on the face..just leading edge and ballance. Followed existing leading edge conture
 

shoboat

Well-Known Member
Joined
Jun 23, 2002
Messages
7,208
Bill,

Your order should arrive on Friday according to the tracking numbers.

Thanks,

Mark Sholund
 

johnmills

Well-Known Member
Supporting Member
Joined
Jan 11, 2015
Messages
58
Not sure BB is still around Dave, seems to me there was a thread on here awhile back that indicated they were no long supplying. To bad, it was great hardware.
FWIW I just purchased some struts and rudders from BB and they arrived in about a week! So they're still in business. The downside is the quality of machine work is a little disappointing and not even close to Speedmaster hardware. I'm sure it'll work just fine though.
 

Wasted wages

Well-Known Member
Supporting Member
Joined
Jan 2, 2006
Messages
2,101
FWIW I just purchased some struts and rudders from BB and they arrived in about a week! So they're still in business. The downside is the quality of machine work is a little disappointing and not even close to Speedmaster hardware.

Thanks for posting this,,, good to know,,,
I was looking at their website and was thinking about buying a few items... but unless there is some difference in the type of metal they use for their parts, I think I will just stick with speedmaster.
 
Top