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270 leg, 4 blade prop

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goatman1

Contributing Member
was running a 280, 1.6-1 ratio leg and a 16x16 3 blade prop
got hull speed at roughly 1500 rpm
put a 270, 2.1-1 ratio leg with a 15x17 3 blade prop
got hull speed at roughly 2000 rpm
25% difference

i only care about max thrust to hull speed, 7 mph
by switching to a 4 blade prop, whats the % gain over a 3 blade
just trying to figure out whether its worth trying a 15.5x17-4 blade or a 15.5x19-4 blade
id probably have to run for 200 hours for the gas savings to pay for a new 4 blade prop
 
Need speed to get the actual slip numbers

Prop Slip

Putting numbers into the calculator at 7 mph,
1500 rpm Ratio 1.6 with 16P = 58% slip
2000 rpm Ratio 2.1 with 17P = 54% slip

Rule of thumb for 4 blade to 3 blade
add 2 inch pitch going from 4 to 3 (19P 4B = 21P 3B) and go the other way when going back.
 
they have Mastercraft wake boarding boats with v-drives in them
i found a 14.25 x 17.5 4 blade. 17 spline
does anyone know if those props have the the same spline as the vp 270?
its a long drive just to go look at it
propdepot.com

OJ 818 WakePro V3 Propeller 14.75" x 17.5" LH Splined .120" Cup

OJ 818 WakePro V3 Propeller 4 Blade 14.75" x 17.5" LH Splined .120" Cup for Mastercraft boats boasts an enhanced pitch distribution along with an improved blade design for better power top and lower. By refining their superior design, OJ has produced a top performing line of propellers. The OJ...
propdepot.com propdepot.com
 
close up of spline
457180493_498949709423436_3903465300344153783_n.jpg
 
VP props ( and most other sterndrive props) have a hub in them that is designed to break a way to prevent damage to the internals.
When and if this happens, the hub is replaceable by any competent prop repair shop.
 
i was kind of curious why they did that
i thought they were just copying the size of the gear case
the splines on the wakeboard prop dont carry all the way through the hub
 
Had a friend grab one for me but they're only 16 spline not 17 spline
i have a scrap volvo prop
it looks like the splines are held in to the outer shell with some kind of filler metal
going to take it to the shop and see if i can get it to melt away with propane or acetylene
ive 3d printed motor shaft couplings before using those rubex kits and machine out the shaft of the nibral prop
 
Yes, I cut one open with a zip blade, the rubbers glued to the outer shell and the internal insert is too large an od for what I wanted. I think there's enough material to broach a vp spline in the nibral but not worth it. Marine Engine has the 15x17-4blade for about $130 usd or about $250 cad after shipping
 
was talking to a machine shop about broaching new splines in
does anyone know the tooling specs or drawings on the volvo penta broaching bit???
 
GPH
My gph doubled at hull speed with the leg change
1500 rpm is 5.5 liters/hr
2000 rpm is 11 liters/hr
We pay $2/liter for gas
I'd like more low rpm thrust and pitch
Had a 280 leg with 1.6 ratio with a 16x16 prop and was fine with that
Now a 270 leg with 2.1 ratio with 15x17 3 blade prop
Like to try a 4 blade 15x17 or 15x19 prop
Solas prop #
8813-143-19
8714-145-17
 
Did you check out "Turning Point" Propellers.. They have 280 drive prop adapters..


Prop part number
21501540
diameter X pitch
15 X 15
prop material
Aluminum
number of blades
4 blades
prop rotation
Left-Hand
Kit is required
Learn More



kit brand
MasterGuard® 510
kit part number
11501000
 
those kits are 15 spline
rbx-127 is for volvo sx 19 spline
i have the 3-1/4 short hub 17 spline
you are probably right about swapping out the ratio
went to vic prop calculator to see what prop spinning at 875 rpm would give me 7 knots and a 15x19 4 blade should do it
thats about 2 gph
 
it does indeed, but im still stuck with one problem, i have to bend the tabs to lock the nose cone in place and that kit has the bolt on nose cone. would that be the 5-3/8 long hub? theres a swap meat at a marina this weekend and ill see if theres a 4 blade 14.25x19 prop there, if not ill just order one. found 3- 270 1.6 ratio legs for a decent price on marketplace. just waiting to see if he has one left
 
i want nothing to do with the border and customs :ROFLMAO::ROFLMAO::ROFLMAO:.
if i see something for sale in usd I just double that and its usually pretty close to what i wind up paying in cad delivered to my door without all the hassle.
 
goatman1 said:
I forgot, Marine Engine won't sell products to Canadians
Click to expand...
It appeared you found a suitable product, but they don’t ship to your address. I merely suggested an easy way to obtain it. Maybe you have a sketchy background, I’ve never run into any hassles with the US Customs people.
 
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