Prop walking F hydro

Intlwaters

Help Support Intlwaters:

Steve White

Well-Known Member
Supporting Member
Joined
Dec 11, 2020
Messages
496
Ive noticed the spin outs with tapered rudders as well, in your opinion (anyone), is there a case where a tapered rudder is a good thing?
Yes, if you want a boat that prop walks and won't run in a straight line they are perfect. Also they have a tendency to hook and spin out in the turns.

Tapered rudder blades don't work well on hydroplanes.
 

K F Wheeler

Well-Known Member
Supporting Member
Joined
Apr 14, 2021
Messages
266
Ok... You guys ARE talking about tapered as looking from the SIDE... Correct?
So who makes a straight blade that will work with the different SpeedMaster rudder brackets????
I'd like to try one. Was going to call SpeedMaster, anyway.

Ken
 

Bradley Maglinger

Well-Known Member
Joined
Sep 23, 2012
Messages
1,611

K F Wheeler

Well-Known Member
Supporting Member
Joined
Apr 14, 2021
Messages
266
Already ordered while talking with Harry.
Not sure your part number is correct... But, Harry knows what assembly I'm running and understands what I'm trying to do.
I've only ever run SpeedMaster hardware so it's easier to talk with someone that knows what you're talking about!
Thanks, Brad!

Ken
 

Steve White

Well-Known Member
Supporting Member
Joined
Dec 11, 2020
Messages
496
Ok... You guys ARE talking about tapered as looking from the SIDE... Correct?
So who makes a straight blade that will work with the different SpeedMaster rudder brackets????
I'd like to try one. Was going to call SpeedMaster, anyway.

Ken
Correct. The leading edge of the rudder, when viewed from the side is parallel to the hinge, the aft edge of the rudder will taper forward from top to bottom. Making the rudder narrower at the bottom.

On hydroplanes this style of rudder doesn't generally work. They may work on mono hulls, I don't know but not hydro's - not in my experience. They will prop walk all over the place and take so much left trim that the trim setting to get the boat to track straight becomes dependent on prop and speed the boat is traveling. The arc the boat travels will be dependent upon the throttle setting.

Use a straight rudder blade and it needs to be deeper than the bottom of the prop in the water.
 

K F Wheeler

Well-Known Member
Supporting Member
Joined
Apr 14, 2021
Messages
266
Thanks for clearing that up for me Steve. Was told yesterday it needs to be 3/4" to 1" longer than the tip of the prop at it's lowest point. Got a new rudder blade on order.
Thanks, Steve. You get that Sport 40 repaired and running?

Ken
 

Bill Eilers

Well-Known Member
Supporting Member
Joined
Mar 15, 2022
Messages
194
Can't say but one thing .Your prop walk and spinouts aren't due to your rudder blade shape. I originally started this post to help me understand what many are thinking. I have seen MANY boats that won't start a turn won't hold a turn won't exit a turn and or spin out. And buy monitoring this post I can see why. First off. With a perfectly linear drive line and surface drive, prop walk will always happen. It's physics that blade will ALWAYS pull the transom.(why do u think we race a right hand track.) Step one you gota have a servo with power (140 Oz d hyd if all else is correct) and get rid of those z bends and flimsy push rods 3/32 680 tig rod threaded for ball links 1/8 for e and f. Keep rods short. There's so much more. Those I've tried to help can't tell me there servo power after plane length cg location or what percentage of after plane there cg is at. Let alone where there turn fin is in relation to cg. Rudders that are not even close to entering the water at 90* then they bring it back out the next time thinking a different prop or rudder will fix it. Your hull designer is the source you should go to for proper setup, if you don't understand how it all relates to a boat that will hold a strait line hands off wheel, enters turn smartly holds that line and exits without issue
 

dwilfong

Well-Known Member
Joined
Jul 1, 2008
Messages
5,900
Stop buying inferior stuff. Get the best and it will run its best........................
 

John Beardslee

Well-Known Member
Supporting Member
Joined
Apr 20, 2011
Messages
1,863
Stop buying inferior stuff. Get the best and it will run its best........................
Stop buying inferior stuff. Get the best and it will run its best........................
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.
 

Tom Foley

Well-Known Member
Supporting Member
Joined
Oct 27, 2005
Messages
6,617
Yes, if you want a boat that prop walks and won't run in a straight line they are perfect. Also they have a tendency to hook and spin out in the turns.

Tapered rudder blades don't work well on hydroplanes.
Been running a tapered rudder for the better part of 20years on my Roadrunner twin and it works well . Old school 805 MG servo on 6 volts it cranks corners very well . I have tried straight as well and very little difference on this particular boat . Rudder depth is critical to avoid prop walk and unplanned spins .
 

Steve White

Well-Known Member
Supporting Member
Joined
Dec 11, 2020
Messages
496
Been running a tapered rudder for the better part of 20years on my Roadrunner twin and it works well . Old school 805 MG servo on 6 volts it cranks corners very well . I have tried straight as well and very little difference on this particular boat . Rudder depth is critical to avoid prop walk and unplanned spins .
In the end, it gets down to wetted area for any given application.
 

rhomodel

Well-Known Member
Joined
Jul 15, 2003
Messages
382
Post us some pictures of the set-up, eg where is the turnfin in relation to the sponson etc. I find it hard to believe a tapered rudder to be the origin of propwalking and spinning. I'm pretty sure it is a matter of set-up where the turnfin is in relation to the CG and how the sponson angles, toe in etc is set-up. and of course shape , angle & sharpness of turnfin...
 

Tom Foley

Well-Known Member
Supporting Member
Joined
Oct 27, 2005
Messages
6,617
Post us some pictures of the set-up, eg where is the turnfin in relation to the sponson etc. I find it hard to believe a tapered rudder to be the origin of propwalking and spinning. I'm pretty sure it is a matter of set-up where the turnfin is in relation to the CG and how the sponson angles, toe in etc is set-up. and of course shape , angle & sharpness of turnfin...
It's not , probably was too short in my opinion . I have had a few hydros that needed about 1-1/2 below the prop to stay on track . I have been using tapered rudders for about 25 years along with straight with no problems . Not saying a straight blade is not better in some cases but tapered rudder blades have been around a LONG time !
 

dr gary turner

Well-Known Member
Joined
Dec 25, 2004
Messages
2,593
I have found IF: the boat is square and set up right(more AOA in the LT than RT sponson) adequate rudder servo power, push rod that doesn’t flex and a good rudder blade/ no slop in it,

The problem is the TURN FIN.

There’s is a lot that is important to the design, placement, positioning(different than placement ) and SHARPENING.

After 20-30 years in boating I learned from someone what it takes to have a properly sharpened turn fin which includes a lot of work/ hours and a good file.

A mill and a mandrel and a fly cutter helps with some of the work.
 
Top