Hello, just signed up. Long time jonboater from Shoals, IN. Mainly run the East Fork of the White River here. This is my setup, which I've had for 4 years. 2005 SeaArk 1872 with 2002 BF200. I ran a 75 for the first 3 years, and I'm currently tweaking my setup with the new motor.
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Hello, new member here from Indiana
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Weldorthemagnificent
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DaveP
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CedarRiverScooter
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Thanks for the hospitality! I came over here from The Hull Truth. Lots of great people there, but not enough Jon Boaters.
Appreciate the comments on my boat. It is my "forever boat."
I ran a 75 for years before I upgraded to the 200. I did not anticipate the combination of boat and motor being this finicky. I've played with props, motor height, etc trying to get it right. It's close now. I'm running in the low 50's, but only at about 5100 RPM. This is with a 19P aluminum 3 blade prop. I added a jackplate, and I haven't gotten a chance to test it since adding that. I am hoping to gain a little RPM and speed. 5100 seems low. But I do not want to go down to a 17P if I can help it.
I've been reading out stainless cupped props. Does anyone have any experience with those? I've had several people tell me that in order to get to 60, I'm going to need one.
Appreciate the comments on my boat. It is my "forever boat."
I ran a 75 for years before I upgraded to the 200. I did not anticipate the combination of boat and motor being this finicky. I've played with props, motor height, etc trying to get it right. It's close now. I'm running in the low 50's, but only at about 5100 RPM. This is with a 19P aluminum 3 blade prop. I added a jackplate, and I haven't gotten a chance to test it since adding that. I am hoping to gain a little RPM and speed. 5100 seems low. But I do not want to go down to a 17P if I can help it.
I've been reading out stainless cupped props. Does anyone have any experience with those? I've had several people tell me that in order to get to 60, I'm going to need one.
Do you know what the recommended WOT is? 5100 seems low? Is it low? Why don't you want to go to a 17P? What is wrong with the correct prop for the set up? Do you have a manual for the motor? Have you read it? With that set up it seems like a nice SS 4 blade would be a good fit, lots of hole shot with that.
surfman said:
WOT is 5000-6000. 5100 is on the low end of that for sure. I've read my manual and adjusted my throttle linkage to make sure it is getting WOT.
I talked to a guy who does nothing but boat props, and he's led me to try a cupped, stainless, bow lifting Mercury Tempest Plus 19P. He believes a 17P would just increase my rpms but I'd still be at about the same speed. I think with 200 horses I should be able to pull a 19P. I think the issue is that the bow drags. I should have mentioned something fairly important. I have a built in 30 gal bow mounted fuel tank that I keep pretty full. I did a run with the tank fairly empty once, and it exceeded 52 mph and had more to go, but it chine walked/prop walked pretty bad so I backed off in order to live longer.
Cupping will typically let you run the motor HIGHER without blowout. But it also reduces RPM a little. 4 blades can also let you run higher.
A SS 4 blade 18p could be a good setup, will run REAL smooth, gets up on the 'pad' quick, and runs higher-if done properly, and the hull isn't too turbulent, may be able to run surface piercing. Most jon's won't allow it but you may be able to fudge the prop and get there.
"MOST" jons have a lot of hull drag as compared to a glass 'pad' hull, and that's where people get the wrong ideas...trying to make it run as fast as a high speed bass boat with the same HP. Sometimes it just won't happen, get into prop walk, cavitation, etc.
The 19P tempest wouldn't have been my choice but it's worth a try. Every hull every motor is different, but I doubt the RPM is going to change much if any. 5100 is real low if that's a light load. With a light load, I'd like to see it up around 6000-ish, maybe slightly over. Lugging (over-propping) a 4 stroke is not good.
There are 18P props made. I ran one on my old glass hull. 19P Tempest was WAY too much (lugged) and 17P wasn't enough. Found a Turbo that fit it in 18P which was right where I wanted it. 90hp Mariner (3 cyl) on a 15' Tide-crap. Topped out right at 59mph on that hull without much "tuning" (motor height).
If one prop is not enough RPM and the next available pitch is too much, you "can" have the smaller pitch cupped which sorta splits the difference. A good prop shop will guide you through it but you need to give them every inch of information that you can accurately get. GPS MPH, gearcase ratios, current pitch, etc. IF they just ask what pitch and what you want, find another shop. There's plenty out there, and there's 2 or 3 here that aren't worth the phone call time.
A customer of mine asked a similar question, 40hp yamaha 4 cylinder (2000 model F40 which is almost the same as an F50), one pitch too much, next available not enough. I suggested Ron Hill propeller and he called, sent it to them, got it back after a full blueprint and re-work for HIS setup, and he picked up 7 mph after raising the motor another 1/2", and better fuel economy, RPM right where it needs to be. That's impressive for a 40hp. No engine changes were made, although it's not hard to convert one of those to a 50. If that motor wasn't so heavy, I'd own one.
A SS 4 blade 18p could be a good setup, will run REAL smooth, gets up on the 'pad' quick, and runs higher-if done properly, and the hull isn't too turbulent, may be able to run surface piercing. Most jon's won't allow it but you may be able to fudge the prop and get there.
"MOST" jons have a lot of hull drag as compared to a glass 'pad' hull, and that's where people get the wrong ideas...trying to make it run as fast as a high speed bass boat with the same HP. Sometimes it just won't happen, get into prop walk, cavitation, etc.
The 19P tempest wouldn't have been my choice but it's worth a try. Every hull every motor is different, but I doubt the RPM is going to change much if any. 5100 is real low if that's a light load. With a light load, I'd like to see it up around 6000-ish, maybe slightly over. Lugging (over-propping) a 4 stroke is not good.
There are 18P props made. I ran one on my old glass hull. 19P Tempest was WAY too much (lugged) and 17P wasn't enough. Found a Turbo that fit it in 18P which was right where I wanted it. 90hp Mariner (3 cyl) on a 15' Tide-crap. Topped out right at 59mph on that hull without much "tuning" (motor height).
If one prop is not enough RPM and the next available pitch is too much, you "can" have the smaller pitch cupped which sorta splits the difference. A good prop shop will guide you through it but you need to give them every inch of information that you can accurately get. GPS MPH, gearcase ratios, current pitch, etc. IF they just ask what pitch and what you want, find another shop. There's plenty out there, and there's 2 or 3 here that aren't worth the phone call time.
A customer of mine asked a similar question, 40hp yamaha 4 cylinder (2000 model F40 which is almost the same as an F50), one pitch too much, next available not enough. I suggested Ron Hill propeller and he called, sent it to them, got it back after a full blueprint and re-work for HIS setup, and he picked up 7 mph after raising the motor another 1/2", and better fuel economy, RPM right where it needs to be. That's impressive for a 40hp. No engine changes were made, although it's not hard to convert one of those to a 50. If that motor wasn't so heavy, I'd own one.
turbotodd said:
I may have to go to 18P, but I'm going to try not to. You may be right that the Tempest won't make a difference in RPM. I'm planning on starting with the jackplate fairly high when I test it. Why do you think 4 blades might help? I thought with a 4 blade prop you generally lose a little rpm and top end. Not saying you're wrong, just wondering and trying to learn.
The whole reason behind getting the most RPMs out of your motor with a minimally loaded boat is to reduce the "load" on the motor, by over propping the boat you are simply adding work to the motor, nothing more. Going to a 17p and increasing rpms means simply that your motor is working less hard. You will see am improvement in performance and even better fuel economy. The 19 sounds like it is getting the job done but I would consider the 17.
A 4 blade and a smaller diameter, just to get better hole shot and on plane faster.
A 4 blade and a smaller diameter, just to get better hole shot and on plane faster.
surfman said:
Performance (holeshot, mpg, etc) is all great. Top end is what I'm struggling to understand. My friend had a similar hull with a 150 HO Yamaha, and he hit 53. That's been my max speed too. I guess I just expected more from 50 more horses.
I hear ya, on making the motor not be "loaded" all the time.
I talked to one guy who said he could go "well into the 60s" with his 1872, 225 hp motor, jackplate, and low water pickup. He said he was a running a 26 (!) pitch Rev 4 prop. Sound likely? Do y'all think a low water pickup will be needed to get those kinds of speeds?
On the other hand, 50+ is pretty darn quick for the river around here, and realistically I do most of my cruising at 25 or 30. I often have kids on board, and I don't want anyone to get hurt.
If he is running a 26 then he is running a LW pick up more than likely and a surface piercing prop, where the exhaust comes out around the prop and not through the hub. His motor is raised up high and only about 1/2 the prop runs in the water. You will want your nose up and you may have issues with proposing with that boat. Your motor is possibly heavier too than the 150 which can also have an effect.
Oh wow, that sounds pretty extreme, and it also sounds costly. I'm happy with my performance really. I don't need to go any faster to be honest. Especially if it costs a lot more $$$. I think I'll just choose to be content with what I have.
