Prop & hole shot

[subkron]

I have a 94 Wellcraft 19 1/2' eclipse w/ 4.3L mecruiser I/O rated at 4400-4800 WOT. Chewed up the two 13 1/2 x 23 3 blade props so a got a set of Pirana composite 14x22 4 blade. RPM @ WOT was 4900 and hole shot doesn't seem as good as 3 blade.<br /><br />Should I go up to 14x24 to keep RPMs in line or would going down to 14x20 give me better hole shot? For the most part I'm pulling a tube or wakeboard and not running @ WOT.

 

[Boatin Bob]

Re: Prop & hole shot

The lower pitch will always give you a better hole shot but if you go lower you will also increase your WOT RPM's. Not sure about 4 blade but as a rule of thumb on a 3 blade you will change 200 rpm for each inch of pitch. Higher pitch will give you less of a hole shot and lower WOT RPM's but you should see an increase in speed. Lower pitch will give you better hole shot and higher WOT RPM's but will lose some top end speed.

 

[jlinder]

Re: Prop & hole shot

Sounds like you are already over revving the engine with 4900 RPM.<br /><br />Lower pitch will just make it worse. I would go up in pitch to get WOT back into range.

 

[subkron]

Re: Prop & hole shot

I guess part of the question is - if I only rev it up to the max WOT point of 4800(even though it could go higher) is that a problem? Or is there a speed-torque issue that I'm violating?

 

[Bondo]

Re: Prop & hole shot

Originally posted by subkron:<br /> I guess part of the question is - if I only rev it up to the max WOT point of 4800(even though it could go higher) is that a problem? Or is there a speed-torque issue that I'm violating?

Nope,..........<br />And,<br />Nope,................<br /><br />Just Be Very Careful.........

 

[umblecumbuz]

Re: Prop & hole shot

Originally posted by Boatin Bob<br />Higher pitch will give you less of a hole shot and lower WOT RPM's but you should see an increase in speed

Although often true, this does not always apply. If your revs drop too much because of running a higher pitch, then the motor isn't developing the needed power (or prop revs) to raise the boat's speed. You end up lugging the motor, which gets you frustrated and does the motor no good.

 

[jlinder]

Re: Prop & hole shot

It seems that if you have a prop where you have to manually keep from full throttle you are not going to get full power from the engine.<br /><br />Not sure, but it seems logical. So why keep the wrong prop on the boat?

 

[Jdeagro]

Re: Prop & hole shot

The lower pitch prop is like second gear in a car. Your acceleration would be better but the engine turns over (rpms) more for every foot of travel. This translates into more fuel used. The top speed will also suffer since the engine will run out of RPMs. Running the engine above the limit is never advisable.

 

[Jdeagro]

Re: Prop & hole shot

Do a search on Trim Tabs for your hole shot.

 

[ramster]

Re: Prop & hole shot

I switched from a 14.25x21 3 blade, to a 14x20 4 blade (michigan vortex) and that made my boat rev to high, holeshot was a little better but cruise rpm's were higher and top speed dropped about 5mph<br />going to try a 14x21 solas amita 4 blade. I have a glastron sx195 volvo gl 220 hp

 

[ufm82]

Re: Prop & hole shot

You may want to try a High Five prop in a 23 pitch. This prop was designed for skiers and wake boarders who want great holeshot and excellent handling. The five blades are smaller but bite the water better due to the extra surface area. I had one on my 20 cuddy w/5.0L Mercruiser and the holeshot was brutal. My top end never suffered more than a mile or two drop either. Cornering was excellent and vibration was nil. Very nice prop for what you want to do. <br /><br />If you were turning 4800 RPM with the 13 1/2 X 23, you may even want to go with a 25 Hi-Five but that may be too strong. You should drop 100-200 rpm with the 5 blade over the 3. <br /><br />E-bay normally has a few Hi-Fives listed at a time. <br /><br />UFM82

 

[txswinner]

Re: Prop & hole shot

I know it is said over and over in this chatroom but really consider Mobster Tabs, cheaper than the prop search and does wonders for hole shot and more importantly for tubing and low speed towing KEEPS THE BOW DOWN SO YOU CAN SEE!

 

[Jdeagro]

Re: Prop & hole shot

If you deside to look at Samart Tabs or Mobster Tabs then Use ST1290-60. Since the RPMs are already too high, the you will need to increase the pitch with the installation of the Tabs as you will pick up another 100 to 150 RPMS (assuming you adjsut the tabs correctly). Do not worry about the hole shot as there will be no hole. You will accelerate just about level, and increase Top Speed.