Prop Question for Tonga

[secondgear]

Tonga I have a 13x19 SS on a 18 ft/1000 lb. Bay boat with Yam/F90 It gets on Plane really good and abt 40 mph/5400 @ WOT. My question Is when I replace my prop should I stay with the same set up? However I would like a little more speed on the top end. With out increasing idle speed 2.2 mph @ 700 What do you think? Thank You SG.:fish:

[ESOX]

Sounds like you have the right prop on there now.

[roger23]

what are your max RPMS for the motor. with a 21 you may over rev the motor If you need more speed you may have to pop for a bigger motor I destroyed a Merc by trying to get more speed I over reved the motor 1 to many times $1200 mistake , Tonga may have a much better answer JUST stay with in your RPM range.

[jpollman]

I think I'm with ESOX on this one. It sounds to me like he's got just the right setup now with the specs he's given. And actually by going UP on the pitch he wouldn't really be in danger of over revving the engine. It would be more likely if he were reducing the pitch.

John

[secondgear]

The max Rpm is 5000 to 6000 So right now I'm right in the middle of the spec. I thought a different prop may 1# Get a little more speed 2# Maybe? A little slower idle speed for trolling. Without throwing all the gear out of the boat that i need to carry. I guess I should have put the 115 HP for two more grand? Many Thanks to all SG:fish:

[waterfoul]

Hello, prophead and former gofast boat racer here.... Going UP to a 21 pitch will DROP your wide open rpm by about 2-300 at the top and INCREASE your idle speed. You may see a slight speed increase on the top end, but is it really worth it? Is 1-2 mph really going to make a difference? How often do you really need to go 41 instead of 40 mph? Your time to plane will suffer with a bigger pitch wheel... I'd say you are about dead on with the prop you have. Live with the current set up or get a bigger motor. On my big boat I have several prop choices... my 22" wheel gets me about 5.5 mph idle speed. My 24" wheel ups that to nearly 6.5 mph at the same rpm.

In short (or is it too late for that? LOL!), stay where you are for a prop. Sounds like a good all around set up.

[Mister ED]

The max Rpm is 5000 to 6000 So right now I'm right in the middle of the spec. I thought a different prop may 1# Get a little more speed 2# Maybe? A little slower idle speed for trolling. Without throwing all the gear out of the boat that i need to carry. I guess I should have put the 115 HP for two more grand? Many Thanks to all SG:fish:

The '92 & '93 are rated at 4500 - 5500 RPM (right out of the factory service manual). Not sure what year yours is, as I suppose they could have changed the top end spec. Might not be a bad idea to double check.

[TONGA]

I'm going to have to agree with most replies and say it sounds like you have a good wheel on her now.
you might be able to spin a 21 but I don't think you we see any real gains,she will come out of the hole a little slower and your slow speed will be faster than you care for.
I like to prop boats to the middle to a little high on the RPM range so the motor dose not have to work very hard, and lets face it 2-strokes love to spin and they don't like to labor or lug.

[secondgear]

Many thanks to all that replyed to my post. The motor is a F90 2003 Yamaha 4 stroke and the spec. was correct @5000/6000 rpm. The old prop is kinda beat up, my fault. So i was thinking of replacing it, but was not sure on the pitch. So with your advice I will be buying a 13 1/4 x 19 which is on the boat now. Thanks SG:fish:

[Mister ED]

Many thanks to all that replyed to my post. The motor is a F90 2003 Yamaha 4 stroke and the spec. was correct @5000/6000 rpm. The old prop is kinda beat up, my fault. So i was thinking of replacing it, but was not sure on the pitch. So with your advice I will be buying a 13 1/4 x 19 which is on the boat now. Thanks SG:fish:

OOPS, Sorry about that .... I missed the F in F90, which is as you stated 4-stroke.

[waterfoul]

Have you checked into having it fixed before you go out and spend a ton of money on a new prop? I'll bet a new one will run you nearly $400, if not more. Fixing a damaged stainless prop will cost less than half what a new one costs...

Of course this is the time of year when the prop shops are kinda busy... so unless you have a backup prop you will be boatless till it's fixed.

[ESOX]

Everyone should have a backup prop. I carry one on the boat and have changed it twice on the water. Two clear choices to me, carry a back up or quit fishing the flats. I'll take the latter.

[roger23]

Carry a spare prop and all the tools to change it.Also extra hard ware to install it .I :confused: had 2 extra props with me I lost a prop out in Lake Erie how I don't know no problem until I realized I did not have anything to keep it on.After having that problem I check the prop and nut/lock washer before I put the boat in the water.I can't belive the tab on the lock washer bent itself up with out help.

[flinch]

Just a thought but if the max rpm on that motor is 6000 and you are only turning 5400 with a 19, going to a 17 should get you in the 5700 - 5800 rpm range, give you an even better hole shot, and reduce the trolling speed. The max speed will remain about the same but there really isn't anything you can do at this point to increase that much.

[secondgear]

Yeah I was thinking of changing pitch to a 17. But I did'th know what my trolling speed would be. I don't want to go any faster when i troll for white bass/hybred stripers.And some times I wish I could go a little slower And going faster would'nt hurt. My thoughts on rpm would be abt 5700/5800 A little closer to the max spec. of 6000. Thanks again to all. SG:fish:

[jpollman]

Actually by going from a nineteen to a seventeen pitch, your trolling speed would actually be a little slower at a particular rpm. You should be able to do the same trolling but actually run the rpm's a little lower. Again, it sounds like you've got the optimal setup already though.

Good luck !

John