New Seapro, prop question

[boling]

While out this weekend, I tried WOT for the first time. Here's what I have:<br />2005 SeaPro 180CC<br />115hp 2S Johnson outboard<br />Cav plate 1 1/2" above lowest part of the hull<br />14X17 al prop (stock)<br />4 people on board, no coolers<br />1/4 tank of gas, oil tank full<br />5800 rpm<br />42mph (GPS)<br />Since I will be using this boat for both fresh water fun(four or more on board) and salt water fishing (two or three onboard), and since I will be getting a spare prop anyway, should I consider a 19" pitch or another 17". WOT range for this engine is 4500-5500.<br /><br />Thanks for the help!

 

[Dhadley]

Re: New Seapro, prop question

I wouldnt go with any more pitch. Youre right where you want to be now as far as rpms go (for longevity of the motor). It sounds as if you may be adding more weight (fuel & coolers) so the r's will drop some. At that point you may want to try raising the motor some to gain some back.

 

[boling]

Re: New Seapro, prop question

Thanks Dhadley, I was thinking the setup would be fine for a load, at 42mph it really felt as if the whole boat was out of the water, I was more or less wondering should I prop up for fishing, where the overall package will be lighter in order to keep from over revving the engine. Isn't 5800rpm a little to high? How high can it safely go?<br /><br />As always, thanks for the help!

 

[Dhadley]

Re: New Seapro, prop question

Over revving a 2 stroke? No such thing. It'll quit pumping air first. As long as theres a load on the prop it'll be fine. <br /><br />I wouldnt worry about it. If it were mine I might try raising the motor a tad to gain performance. Your slip numbers are pretty good now at about 11%.<br /><br />Now, if youre going to buy another prop and use this for the spare (good idea), I might think about a ss 19 but ONLY if youre going to work the set up to get back to 5800 with an average load. If you have no intention of changing the set up I'd go with a 17.

 

[boling]

Re: New Seapro, prop question

Most likely I'll get a 17" spare, sure beats having to paddle home. Is it true that a same size SS prop will increase rpm because it provides less resistance having thinner blades? Is there a particular SS prop that would work well here? 3 or 4 blade? Or should I just shutup and get another al. prop exactly like the one I have? Not likely to change motor height at this time.<br /><br />Any tricks on getting the speedo cable (tube) out of a bind? Looks like it's crimped just as it passes under the carbs headed down the shaft, most likely at the seal(Very hard to reach). Maybe I'll get the dealer to handle that one during the 20 hour service.<br /><br />As always, thanks

 

[Dhadley]

Re: New Seapro, prop question

The same size ss prop will most likely drop rpms slightly because there is less flex. The stainless is better suited for some of the higher tech blade shapes too. It all adds up to "bite".<br /><br />If youre not going to dial in the set up then just stick with a replacement style ss prop like an SSTII or a Stiletto. No sense paying for the technology in a Turbo or even in a Raker since you dont plan on taking advantage of it. <br /><br />A good 4 blade like a Stiletto or a better 4 blade like a Turbo is definately out of the "suggestion box". Again, dont pay for technology you arent going to use.<br /><br />But dont be surprised if you talk to someone one day with the same rig and they get a better holeshot, more top end, better fuel economy and better a cruising speed at the same rpm. Most likely that guy will not have an Evinrude like you and you'll end up thinking "brand X" just does better. It may not be so. His set up may just be better.

 

[boling]

Re: New Seapro, prop question

Understood. I fully expect to see better setups, knowing I'm in the balpark will be ok for right now. What do you see as a potential top speed after tweeking the setup? 46? 50? <br /><br />Maybe later on, I can launch a better argument for tweeking funds from the financial consultant(wife). I will be testing with a load this weekend, will report back with numbers. Finally off the pre-mix!!!

 

[Dhadley]

Re: New Seapro, prop question

Just as a reference, with the 17 at 5800 rpm your theoritical speed is 47-48 mph. With a 19 at 5800 its 53. So using the same (assumed) 11% slip youd be about 47 mph.

 

[boling]

Re: New Seapro, prop question

Update: This past weekend, I took it out, 2 of us onboard, 1 cooler, and 3/4 tank of gas. At 5900 and GPS 41 Mph, it would ventilate with just a touch of the steering wheel, or any small wake from another boat. I would assume by this, the motor is as high as it will go. Do I try to shift weight to the back in this situation, or do I seek a prop with more bite?<br /><br />Still yet to decide on what spare to get.<br /><br />Thanks for all the help!!!