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  1. #1
    Member River Rocket's Avatar
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    Fastbass Marine TV - Battery Placement Testing

    As most know I have struggled to get the new R to run with my old 300XS DBR. In all the testing I have done it has always come down to hole shot. The motor pulls just as well from 15-top, it just loses it in the hole shot. Unlike the XS it doesn't bog, but instead goes nose high then comes down after climbing a wall of water (and I have wedges). This rise takes time and as a result when compared to the 300XS DBR the 300R gets to speed slower in the 5-XX comparison and in the time to a given distance.

    On my boat it is stern weight. The added motor weight made a difference. Jay is seeing this as well on his 2+2 300R. I decided to test other configurations to see if I could improve the holeshot.

    For this test I made battery trays for the nose of the boat. My boat had two sets of trolling motor cables so I re-purposed one set and ended it in the bow. I did some jumpering and added a second breaker so I could switch batteries locations on the water and still fish. I also added cables so I could move the starting battery to the nose as well. Now that I have a lithium troller I can either run all my batteries in the nose or everything in the rear or a mix. The plates and additional wiring weights 10lbs. I took it a little far......

    This test shows back to back testing of a 28 Promax with forward and aft battery placement. I made one pass with 130lbs of batteries in the nose and followed that up with one pass with the batteries in the back of the boat. I used a 28 because it hits the limiter fast and it would be easy to see how battery placement impacted 5-85 times, time to distance, and closing speed.

    Despite the small pitch the results were the same with every prop I own. Bow mounted batteries had a slower top speed by 1-3mph depending on the day. Bow mounted batteries always got out of the hole faster. Bow mounted batteries always made the boat feel less responsive and loose (this can be seen in the slower acceleration curve after 50mph). The higher the pitch the longer it takes for the aft located batteries to catch the bow batteries. With the 30 Promax it happened fairly quick and the 32 promax took over 1/2 mile to catch up. Having the batteries in the nose allowed me to run a 32p on tournament days with a full live well vs. a 28 with the batteries in the back.

    I will say that I was surprised that all the props I own still carried the weight fine and could pull awesome speeds despite the 140lbs of added weight in the nose. After this test it was clear to me that lithium was the answer. I have the lithium testing and video done. I will put it out soon.

    These boats are super impressive with all that weight in the nose.

    Last edited by River Rocket; 09-16-2019 at 10:28 PM.
    Allison XB21 2+2
    Mercury 300R




  2. Member fishnfireman's Avatar
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    #2

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    #3
    Have you thought of putting one trim tab under the jackplate? Instead of tow like the gamblers the ally should only need one. Just a thought.

  4. Member tritontr21's Avatar
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    #4
    Quote Originally Posted by chad202 View Post
    Have you thought of putting one trim tab under the jackplate? Instead of tow like the gamblers the ally should only need one. Just a thought.
    That theory has been tested as well. The skid planer the XB21 has pretty much does the same thing.
    Jay McDaniel
    2003 Allison XB21 BasSport Elite 2+2
    2019 Mercury Racing 300R

  5. Member River Rocket's Avatar
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    #5
    Quote Originally Posted by chad202 View Post
    Have you thought of putting one trim tab under the jackplate? Instead of tow like the gamblers the ally should only need one. Just a thought.
    As Jay mentions I tested the heck out of that. Went several design iterations into it. The Allison skid planner behind the pad of our boats does the job. I couldn't find the holeshot plate doing anything positive on my boat aside from removing low speed porpoise when pulling tubes. Did an awesome job at that.

    IMG_8959.jpg
    Allison XB21 2+2
    Mercury 300R




  6. Member River Rocket's Avatar
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    #6
    You can see a couple of cool things in the graph. I believe the heavy nose causes the stern to lift. You can see the water pressure is lower as a result. Slip also gets impacted and goes up. When slip goes up top speed goes down.

    The yellow line is the lead in feet that the nose battery has. You can see it jump way out in front and the stern battery chases it down. In the 50 to 60 mph range you see the time to speed lines over lap and then the distance starts to narrow.

    bow vs stern batts comparison graph 2.JPG
    Allison XB21 2+2
    Mercury 300R




  7. Member K-DAWG's Avatar
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    #7
    So did the 32 give you the same top speed as the 28? Which set up did you prefer, the 32 batteries in the nose or the 28 batteries in the rear? Thanks for all the testing you do.

  8. Member River Rocket's Avatar
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    #8
    With batteries in the rear or nose I see about a 5mph bump with each prop

    Batteries in the back
    28 promax best of 90mph. Typically 89
    30 promax 96mph. Typically 95
    32 promax 100mph Typically 98/99

    with batteries in the nose
    28 promax was typically 1mph slower
    30 promax was 2 mph slower.
    32 promax was 3 mph slower.
    The 30 and 32 were significantly slower in acceleration from 50mph and up as well.

    I stuck with batteries in the rear for day to day runs and only moved the batteries for tournaments when I had a partner in the boat. If I was solo tournament fishing I would run a smaller pitch with back batteries. I liked the sporty feeling back batteries provides and I’m a top speed guy. If I was racing myself from an idle, I would lose 100% of the time with batteries in the back (same pitch prop). Batteries in the nose are just that quick out of the Hole. The data pissed me off a little. I was really hoping it wouldn’t be as clear. The 28 with batteries in the back is close to a 32 with batteries in the nose. Bottom line I just don’t like the slow acceleration after 50.
    Allison XB21 2+2
    Mercury 300R




  9. Member fishnfireman's Avatar
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    #9
    .
    Bottom line I just don’t like the slow acceleration after 50.
    SLOW ?
    You would still blow by anything except a drag boat..

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    #10
    It's interesting that at about 9-10 seconds or around 55 mph the slip/mph numbers switch between the bow and stern and the rpm stays really close throughout that entire range. It is almost like you can envision the boat 'tipping forward' slightly becoming less efficient as that transition happens. Really cool data! Also makes me really impatient to get a bigger motor on my 2003, the 150 accelerates nicely but I can't wait till I get that type acceleration. Your quarter mile time is close to some 70's muscle car numbers.

  11. Member River Rocket's Avatar
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    #11
    Quote Originally Posted by ntxwaterfowl View Post
    It's interesting that at about 9-10 seconds or around 55 mph the slip/mph numbers switch between the bow and stern and the rpm stays really close throughout that entire range. It is almost like you can envision the boat 'tipping forward' slightly becoming less efficient as that transition happens. Really cool data! Also makes me really impatient to get a bigger motor on my 2003, the 150 accelerates nicely but I can't wait till I get that type acceleration. Your quarter mile time is close to some 70's muscle car numbers.
    You are also seeing the limiter. It holds me at around 6450 and bounces a little. The motor is pulling power to keep the RPM down. I hung it on the limiter so I could test how long it took for the rear batteries to catch up.

    On big wheels what you will see is the slip is high when you hit the limiter, then it drops and speed builds. Unlike the opti, you can hang on the limiter and see this effect. Its really cool with the 30. It will hit the limiter around 93 and climb right up to 95/96 all while on the limiter. I think that is the hull picking up and becoming more efficient and the slip dropping.

    FYI, I did find that it will pull power with force if you hold it on the limiter too long. Very similar to how you feel the opti cut power. I have only seen this with the 28 as it can blow right by the limiter. The 30 and 32 are big enough they don't seem to want to push beyond the limiter as much.
    Allison XB21 2+2
    Mercury 300R




  12. Member white gambler's Avatar
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    #12
    RR any testing on odd pitch promax's? Curious if the boat likes the even (less cupped) pitches for any particular reason.
    24’Bass Cat Puma Sts-300 Proxs
    23’Gatortrax Gt tunnel hull-200 Suzuki

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    #13
    Quote Originally Posted by white gambler View Post
    RR any testing on odd pitch promax's? Curious if the boat likes the even (less cupped) pitches for any particular reason.
    Promax’s even pitches have more cup than odd pitches. Bravo1XS’s it’s the opposite.

  14. Member tritontr21's Avatar
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    #14
    Quote Originally Posted by white gambler View Post
    RR any testing on odd pitch promax's? Curious if the boat likes the even (less cupped) pitches for any particular reason.
    The only odd pitch Promax we have tested was a 27 and it was to small for both back when we were running Opti's. Especially with my 250/1.75's. Ran good till the limiter shut me down.
    Jay McDaniel
    2003 Allison XB21 BasSport Elite 2+2
    2019 Mercury Racing 300R

  15. Member white gambler's Avatar
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    #15
    Quote Originally Posted by rocketmanjp View Post
    Promax’s even pitches have more cup than odd pitches. Bravo1XS’s it’s the opposite.
    Interesting. Good to know. I was basing that statement from my experience with Bravos. Assuming it translated to most merc props
    24’Bass Cat Puma Sts-300 Proxs
    23’Gatortrax Gt tunnel hull-200 Suzuki

  16. Member fishnfireman's Avatar
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    #16
    I had been told that Merc got the odd pitch numbers by adding cup to a lower pitch.
    I have 3 odd number Pro max props, they were cast as 1 pitch higher then re stamped to the next pitch down at the factory.

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    #17
    Quote Originally Posted by fishnfireman View Post
    I had been told that Merc got the odd pitch numbers by adding cup to a lower pitch.
    I have 3 odd number Pro max props, they were cast as 1 pitch higher then re stamped to the next pitch down at the factory.
    This theory is true for bravo1xs but odd pitch promax’s have cup taken away from the next largest even pitch.