Tested the 19 pitch 4 blade I got 38.5-40 two people going up river and about 39 in about a foot or so chop on the main lake, and 41 solo. Lost a little top end but I hit 5100 (out of 5250) roughly. I think that’s the ticket
You may be able to bring the 21 into a prop shop, and have some pitch taken out of it as well.
My mechanic mentioned this yesterday when I picked up the 19 spitfire to test. He said about 250 Canadian. See what happens with the 19 first
Given the boat is underpowered compared to the the max HP of 150, I would start by replacing batteries with Lithium phosphate. I have a ranger boat, over the years increased from 80lb 24v motor to 36 v 112 lb. Added 31 class batteries to power it and upgraded from 3 bank to 4 bank Dual pro professional series. I also upgraded to a 31 class AGM for my cranking batt. I installed much larger helix graphs up front and console. All in all I added at least 250-275 (maybe 300) lbs more weight than the boat was initially designed to accommodate. The boat sat low in the back end. My hole shot dropped terribly, the boat handled terrible too, the back end would not stay hooked up, prop would blow out. This year I installed a single 36v 60 ah lithium phosphate and backed down to a 2 bank 12/23v onboard charger. I had to move some things around to rebalance the boat. I have a new boat, from a performance standpoint it is like new again. No blow out, great hole shot higher top end by about 5 MPH. To me weight is the first place to look any time you see performance changes. Something to think about. That boat when new with the 115 2+2 was rigged with a 12v bow motor and some sort of small sonar. More than likely the batteries were 24 class. You have added some weight to that boat over the years.
I have considered this as well, I probably have double the weight in electronics and trolling and the batteries to run said equipment than what they used back then when the boat was designed. Unfortunately I replaced my trolling motor batteries and the electronics battery last year and the year before when they were in my old boat, so I would have to wait before I can even consider that. With that said I would like to replace with lithium one day.
2 pitches down will add about 400rpm to WOT, should give you slightly better hole shot, top end might suffer 1-2mph. But are not racing so how cares as long as your just shy of Red line and you can hold the bow down.
I relaize I will get 400 or close to up going to a 19. Which is my concern of being at or over 5200 causing redline. I wish they made the spit fire in a 20, I feel like it would be perfect.
Tonight I tested a 12.8×21 4 blade spitfire x7. The boat had the best handling since I have got the boat. The bow was out of the water, wake was out the back finally like it should not forward of the windshield. I ran full tank and full gear with my self and a passenger. I ran 4800 rpm at 41.4
When it came to load up I dropped off the passenger to get the truck I took it for a rip. 4800 rpm 42mph. I think I will the 19 pitch and compare. 19 should put me at 5200 which is my peak rpm. How much mph would I loose going to the 19. Hole shot was a tad slower than what I had before but it wasn’t horrible and didn’t struggle either rpm range is 4750-5250
Have you put a straight edge to the bottom of the boat to make sure the hull doesn’t have a hook in it? That would definitely cause your bow lift issues.
As a FYI the general rule of thumb is a 3 blade prop give bow lift and 4 blades cause stern lift. My boat is a good example of this. With a 4 blade prop my boat wants to run flatter and starts porpoising at lower trim levels. With the 3 blade the stern settles and the bow lifts much better.
I actually didn’t know that. I always thought 4 blade had better lift
<div class=”d4p-bbt-quote-title”>Salvatore wrote:</div>
3 batteries in the very backWell, there’s that. What group size
3 group 27 agm and 1 group 24 lead acid for the cranking battery
<div class=”d4p-bbt-quote-title”>Salvatore wrote:</div>
. I dont struggle to get on plane. It’s more the last little bit of lift I need for it ride properly.Have you considered your weight distribution, battery and gear placement?
There isn’t much I can move. The front has 2 storage and a live well. I don’t use the livewell for the reason of the weight. The other compartment has maybe 25 lbs of tackle and a spare prop and bailing kit. Very tip of the bow I have my anchor rope and foot pedal.
3 batteries in the very back, and 1 between the dash.
That X7 4 blade prop is the way to go, that s what I have and am very happy. Boat pops out of the water. Also look at the motor height as that effects the ride also.
Did you notice a difference in how lift and a postive top speed going to the x7 or did you lose top end
I havent. I dont struggle to get on plane. It’s more the last little bit of lift I need for it ride properly.
I understand the dash reading is out and I wonder if that’s where Lund got there number of 42 from and 37/38 is all I will get out of mine on gps
Motor is mounted in the second hole as per Lunds recommendation
I will not lie I am trying to squeeze out the most performance out of this ol girl but over anything the boat handles like crap with a black max prop and the laser 2 I was offered for half price as new and the vengeance was even cheaper. This boat seems to require a prop that has lots of bow lift. I would love to see 40 solo and 38 fully loaded with fuel and 2 people, but yet be able to keep the boat fully out of the water. The laser 2 accomplishes this for the most part if I was solo but it didn’t like 2 people in the boat. I’ve reading the spit fire x7 doesn’t cost you top speed and offers good bow lift
I’m not opposed to a aluminum I just want the best lift yet keep my top speed as well
Curious of this as well, as I do realize I do have a lot of weight in gear and will only get heavier adding a bow graph next year. But I do read that this boat is 42mph from factory I assume that is a dash reading not gps like mine.
If I can get the bow lift I want I will probably settle for that to have better handling. I don’t know if a aluminum will give it tho
