Bob B. - Is there a "point of diminishing returns" ?

[TritonGlenn]

Something I've wondered about for a few years...



I'm actually fairly happy with my current setup, but as always - trying to get more when I can. Holeshot could be better I think, and I would like to make sure I'm wringing everything out of it that I can.



2005 Triton TR-20X, 225 Optimax (regular, not XS), Bobs Machine Shop 10" hydraulic plate.



Originally, when living in Virginia, I had a T&H Marine Pro Hi-Jacker manual plate (6") on it. Ran fine, but very prone to chine walking. I threw some 2" Bobs Machine shop spacers on it, and it ran perfect. Best speed I ever saw with a 25" PowerTec TRO-4 was 74.9 on GPS - that was pretty much empty too. I couldn't quite get that with my 25" Trophy. Small tool box, few rods, light tackle, low on gas. Single console at the time. Decent holeshot. Called PowerTec. They were amazed I was getting 74.9, and said that was beyond what they calculated it would do on my hull.



I added a second console and lost a few mph on the top end without doing anything else. Max I could wring out of it was 72 with a light load.



Changed to a 8" (actually 7 1/4" when measured) Detweiller hydraulic plate. Hated it. Never really did top end runs because of all the issues I had with it. Send it back.



Changed to a 10" Bobs Machine hydraulic. Nothing else changed. Top speed was still about 72/73, but my hole shot didn't seem as good. Played with height and trim, but couldn't quite get my old hole shot back.



Moved to Texas. Hole shot went to crap. Took FOREVER to get out of the hole. Surprisingly, changing to a 24" Fury fixed my holeshot problem quite a bit, and put me at a top speed of about 71mph with a half tank and light load. I hit 5750 and get the warning buzzer, but know it's got more in it. I tried a 25" Fury and hated it. The boat felt very "loose" in the rear, like it was shifting side to side on a horizontal plane. Not chine walking though - it was a very different feeling that I've never experienced before. Couldn't get more than about 5400 out of it if I remember right. I know I wasn't hitting max RPM's though and the boat was difficult to control.



Long way around the question, I know, but that's what I'm known for here (ask Toxic) - details! :lol:



Do you think I hurt myself going further back, and should have stuck with 8" of setback?

Do you think I could do better, or am I pretty much at max for my setup?



I'm happy with it - just want an expert opinion.



All the best,

Glenn

 

[Bob Bourget2]

I LIKE details! Good job....

NOW....sounds like you've done your homework but I do have a few pointers.

1. You're not done experimenting with props. I can't see in your arsenal if you've tried a TEMPEST. A 25" at that. See if someone has a virgin copy you can try.....OR.....it'd be nice to see a Mazco 26" RE on that rig.....:blink:

2. No mention of water pressure. I'd keep jacking it up 'till you see no LESS than 15psi, or speed drops off.

3. Bottom. Is yours straight? LOL. Last four feet, by three feet off center to either side of pad.

4. You MIGHT benefit with a coned case. I know you'll hear all the stories about "80+"...BUT....we did a test for Bass'N'Walleye entitled "nose cone shootout". The specs can be found on Bob's machine shop web-site. We tested CLE, Land'N'Sea, Bob's, HydroMotive, Stock {2.5 / 150}, and found that on a NITRO 190 SC with a BONE STOCK 150 EFI, we could and did achieve a higher top end than a non-coned case. If memory serves me correctly, we took a stock speed from about 69MPH {radar} to an astounding 74ish! The boat was equipped with a para-lift jackplate, and was pretty much stripped down to just the "boat".

I feel it can be improved upon....keep going!!!

 

[TritonGlenn]

Bob,

Thanks for the reply. To address your questions and courses of action:



1) I tried a 25 Tempest when my boat was new. It gave me the same top end as my best props, but the hole-shot sucked big time. Maybe it's just the one I borrowed. My buddy had a TR-21X with the same 225 that I had - same year as my boat. With the 25 Tempest on his boat, he pulled away from me just every so slowly. We swapped props and I had a hard time coming out of the hole, and top end just wasn't the same. If I recall correctly (that was 5+ years ago), I wasn't turning it at max rpm. Regardless he always pulled away from me in that 1 foot longer boat with the same engine. I've never tried a Mazco prop. I'll look around to see if I can get my hands on one. I've got a few good prop guys, so I'll give them a call and see if I can get a loaner.



Odd, but my boat has always (from the very beginning) turned slightly lower pitches than comparable boats. When someone recommends a 26 pitch, the 25 pitch in the same prop always worked better for my boat for some reason. Might be all the Chinese food sitting in the drivers belly. I can't know for sure. :lol:



2) I can't recall my water pressure tonight. I used to have it marked and watched it religiously, but I've been a very bad driver lately and haven't been looking like I should. Once I had my jackplate set at a height that gave me the best speed and still maintained at least 15psi, I left it there and only seldom ever change it (rough water, etc...). I have to find my little sheet of paper that has my readings from pad versus psi to tell you what it is for sure. I always just set it at the 3 3/4 mark on the digital Bobs Machine Shop gauge and hammer it lately. I'll look for my little laminated sheet of paper and I'll re-verify next time I go out.



3) My bottom is straight and very lightly scuffed. Verified and checked for straightness periodically. I researched this quite a bit when looking into performance back in 1994 or so. I have seen first hand what a slight hook can do to performance on a Cajun bass boat. I verify mine with a straight edge (48" long level) and I do a very light scuffing with scotchbrite on it when I clean up my boat.



4) Interesting. I wasn't thinking of going as far as putting a nose cone on, but I just might if I have some extra cash laying around during hunting season this year. Maybe a winter project.



What did you think of the jackplate setback? Am I ok with the 10" I have, or should I order some 8" sideplates from Bobs and rebuild it with less setback? I'm not sure if the 10" gives me any advantage or disadvantage.



All the best,

Glenn

 

[Bob Bourget2]

The "ideal" set-back {weight distribution}, will yield a boat that runs to it's max speed with perhaps one degree of trim. You want the prop pushing you forward instead of wasting energy holding the bow up. Have a peak at my Allison in my library and you'll see what I mean. If your boat runs WITHOUT needing max trim, you are getting there. That Nitro 190 that did 74 had a para-lift which has about 18"!! :blink:I think with some prop choices, there's more to be had....especially with the over-hub design. I failed to mention the other shoot-out we did for B'N'W was props.....and the winner was the Mazco RE3.....and....that was on a Nitro.



EDIT: In answer to your question.."is there a point of diminishing returns?"....YES.

 

[Rob LaMoy]

It's usually right after you say, "I do." :lol: