Yamaha F150 Prop Help

[fightindablues]

Its on a 19' Polar CC. Depending on the amount of people, gas, lots of batteries and fishing gear and amount of water in the bait tank it weighs anywhere from 3500 to 4500 or so pounds. The current prop is a 14.5" 19 pitch. Planing speed is very poor. Top speed is 40.2 mph at 5300 rpm. I borrowed a 14.8" 17 pitch from a friend and tested it out today. Plane speed was a little better but what surprised me was the lower pitch actually increased my top speed to 41.4 mph. The rpm maxed out around 5500-5600.

While I'm happy with the increased top speed, the hole shot is still not where I need it. My question is, is it time to go with a 4 blade or a lower pitch 3 blade? I have a feeling that a lower pitch 3 blade may still not give me the wholeshot i need when fully loaded but I'm not a prop expert so any suggestions are greatly appreciated. Both props I've used are aluminum and that's what I'm trying to stick with.

Thanks

 

[steelespike]

Are the props the same brand and model?
What is your actual hole shot time?
Your 19" has about15% slip your 17" has about 8% slip unusually low but possible.
The higher rpm may account for some of the improvement.
"Lots of batteries" sets off a suspicion you may have a poor setup
with a stern bias weight distribution.
Are you sure the motor trims down all the way?
Some motors have a base adjustment that may allow more down trim.
I checked a couple of generic 150 hp testsDry weight from 2000 to 3000. 3000 lb had 4.98 hs.lighter boats 3.5,3.54.
I figure the 3000lb boat must be close to 4000 with all gear motor etc
A 4 blade should help your hole shot perhaps a 16".
You might consider" smart tabs" Haven't seen them suggested in a while.

 

[fightindablues]

Thanks for the reply. The 17 pitch that I borrowed is an Evinrude, the 19 is a Quicksilver. Don't know the exact time to plane but roughly just under 4 seconds with the 17 and just over 4 seconds with the 19. Those tests are just me and some fishing gear. I have not tested the 17 with a full charter group yet. The 19 with a full charter group has taken as long as 8-10 seconds to plane with a large charter group. That leads me to think that although the 17 would be a little quicker, it still won't be enough. The batteries are mounted under the console which sits almost in the middle of the boat. Yes the motor does go as far down as physically possible. I know I can't have the best of both worlds but I'm trying to loose the least amount of top speed as possible because of long travel times but also trying to keep the motor from begging for mercy to get on plane when I have a large group.

A brief history on the boat. I got the boat and motor new in 2005. It came with a Yamaha 21 pitch prop, it was slow to plane even with light load but top speed was 43 mph so that was tolerable. As my charter business grew, so did the weight of the gear and groups so I went to the 19 pitch about 4 years ago, it improved the wholeshot only slightly and decreased the speed to 40ish depending on wind. Now I'm upgrading to a larger bait tank so I've got to get more wholeshot. I'm having a hard time finding a 16 pitch 4 blade to fit the f150.

 

[steelespike]

Your hole shot performance Is on par for other F150s on on 19 and 20' boats at about 3500 lbs total. 3.93 sec,3.28, Highest was 4.75.Most with 17 or 18" props
Top speeds on weights close to your light loads with 17" were 43.8 to about 45.I wonder if your bottom may be a little rough?
Its my feeling your better off with a 17" though it will probably be hard to match your test numbers.
If you go to a 4 blade you will very likely lose another 1 or 2 mph.
The 4 blade Merc Spitfire prop is said to maintain rpm so a 17" might give you better hole shot yet maintain speed.

 

[fightindablues]

Thanks for your help. I finally found the mercury spitfire you were talking about. It doesn't say in the description if it fits my motor. It does come with a hub kit that looks very similar to the kit that came with the Quicksilver prop so hopefully it does fit???