etec 75 set up and prop questions

Discussion in 'Prop Shop' started by levip, Mar 30, 2012.

  1. levip

    levip I Love microskiff.com!

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    so i got my new motor friday (YEA!!!) ive got a few loaner props from friends and the dealer
    right now im running a 14x17p aluminum and it seems to give the best rpm out of all the props ive run so far HOWEVER at 4900 WOT rpm im still a couple hundred rpms too low, reccomended WOT rpm is 5250

    #1 will i gain or loose RPM going from aluminum to stainless ??

    #2 how many rpms will i gain going down in diameter 1"?

    #3 ive ordered a 13x15p four blade rogue do you guys think im gonna be where i need to be with this engine?

    #4 how can i tell if ive got my jackplate up too high or if i need to go up a hole to lift the motor higher?

    #5 ive got trim tabs also, how should i run those when running at WOT all the way up ? straight out the back ? down a bit?
     
  2. levip

    levip I Love microskiff.com!

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    ps i LOVE my new etec

    pic of me cheesin after a great day on the water:

    [​IMG]
     

  3. Brett

    Brett > PRO STAFF <

    Cheesy is the right word... ;D

    #1 will i gain or loose RPM going from aluminum to stainless ??

    Stainless allows for thinner blades, less friction = more rpm's

    #2 how many rpms will i gain going down in diameter 1"?

    About 200 rpm change per inch of pitch change

    #3 ive ordered a 13x15p four blade rogue do you guys think im gonna be where i need to be with this engine?

    Only on water testing will tell.

    #4 how can i tell if ive got my jackplate up too high or if i need to go up a hole to lift the motor higher?

    If you're pushing air you're too high. If water pressure to the powerhead drops you're too high.

    #5 ive got trim tabs also, how should i run those when running at WOT all the way up ? straight out the back ? down a bit?

    For best speed you want to have the tabs up as high as possible without porpoising.
    Adjust down to fit sea conditions and to balance uneven hull loading.
     
  4. levip

    levip I Love microskiff.com!

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    firstly THANKS BRETT!!!!

    yeah i was confused because my dealer said id turn less going to stainless because the aluminum flexes more -made sense to me but so does the thinner blade thing so???

    #2 was will i change rpm by changing diameter? - i got the pitch thing figured
     
  5. Brett

    Brett > PRO STAFF <

    All I've ever seen was pitch change to rpm change.
    Diameter change was all about tip speed and wetted surface.
    Diameter being limited by anti-ventilation plate to shaft dimensions and engine horsepower.
    Reading suggests only a change of 50 to 75 rpm due to diameter change.
     
  6. levip

    levip I Love microskiff.com!

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    alright cool good to know
    they make props from 12- 14" in diameter and the gearcase can swing up to a 14 1/2" diameter prop
    im looking at a viper if the rogue doesnt work out i can swap tit for tat anyone on here running one?

    i tried a 19 viper but it was WAY too big
     
  7. b16stang_crx

    b16stang_crx I Love microskiff.com!

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    man ive been prop testing the past month and a half even far as going out on a thursday or tuesday after work and testing at night lol, i bought a BRP prop and going thru the demo props, so far on my set up (16ft flats with a 115hp evinrude) the best results was a viper 13 7/8dia with 21 pitch got the boat to 50-51mph timmed wot 6k rpm BUT the holeshot is horrible, i just got a 4blade rogue 15 pitch they gave to me to demo but it was useless 6k rpm at half throttle 36mph triimed all the way down im kinda stuck now also because they dont have any more 4 blade demos because other people have them and dont return them, im so fustrated with all this prop crap
     
  8. levip

    levip I Love microskiff.com!

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    lol yea i feel you, my dealer sent my new one to the wrong adress yesterday ... good news its going to my moms bad news i gotta pay to ship it back to savannah .... sux

    id try a bigger rogue though Ozzy theyre sposed to be the shizz especially for a flats boat theres some guys on here that have em and depending on local might be willing to lend you one for a test spin .... ill let you know how mine works out though if i ever get it ....

    as for the outta stock props you might wanna put the call into BRP's customer service and put a bug in their ear about said dealer .... ESPECIALLY if hes a "BRP DEMO prop dealer" ... thats bs and you and i know it if hes a demo prop dealer hes gotta keep EVERY prop BRP make IN STOCK at ALL TIMES ... that or hes a moron and just goes around all willy nilly loaning out props without getting at least a copy of a drivers license or something at 600 bux nearly a pop id have the cops at those guys doors telling em whats what and they had 24 hours to return em or find themselves in an 8'X 8' ya know?
     
  9. b16stang_crx

    b16stang_crx I Love microskiff.com!

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    the way this dealer works is you have to buy the prop... and then they give you the demos untill you find the right one..... and yea im probably going to have to go with the rogue 19 or 21, and I didnt think about calling brp diret...maybe they can send them a demo prop for me
     
  10. levip

    levip I Love microskiff.com!

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    yea some of those demo dealers dont like to keep everything theyre sposed to have on hand .... i understand its ALOT of overhead but thats the way its sposed to work....
    as for a correct prop im thinking a 17 rogue is gonna be your critter.... 19 or 21 will be too big even for a 115 and like i was saying you wanna prop to the high side unloaded so that when your loaded down your still on the high side of the operating range
     
  11. cutrunner

    cutrunner Cert. Yamaha technician

    Didnt know sundance made a v hull. Its a cool looking design.

    On another note, now it all makes sense...
    You mentioned you know ken.
    Now that you put up a picture of yourself i recognize you.
    Your Fidanzas buddie. Remember that night you guys were putting a water pump on his van, and some ass hole in a black mustang came to help? That was me :eek:
     
  12. levip

    levip I Love microskiff.com!

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    oh ok yeah now i remember you....

    yea its a nice boat it one of their earlier designs the hulls a 1996 model its got a pad on the bottom of the hull too so far with a 17p aluminum weve got it up to 34.5 mph loaded with three people and a 100 lb cooler burning 7.66 gph @ 4900 rpm - im loving the Icommand gauge
    new prop is on its way and should be here tuesday and a wet test will follow

    anyone know how high the engine should be with 8 inches of setback??
     
  13. Brett

    Brett > PRO STAFF <

    The vertical reference points are the underside of the anti-ventilation plate
    and the bottom edge of the transom. Based on a 5° hull running angle,
    the starting point for fine tuning works out to about 1 inch of lift for 12 inches of setback.
    That horizontal distance is measured from the bottom edge of the transom
    to the centerline of the water inlet.
     
  14. levip

    levip I Love microskiff.com!

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    ok cool brett i was looking friday while we were running WOT and the cav plate was not visible with the jackplate all the way up so im guessing i need to come up higher on the motor? im already about 2 inches above the keel with the jackplate up all the way.... seems like it wants to get squirrley though so?
     
  15. Brett

    Brett > PRO STAFF <

    Had to understand this too a while back...

    http://www.microskiff.com/cgi-bin/yabb2/YaBB.pl?num=1235777190

    Control is critical! If you feel unsafe, drop back down a little.

    Looking at the picture you posted, part of the problem may be how far the engine is tucked in.
    Trim out until the propshaft is parallel with the line of the keel.

    [​IMG]
     
  16. levip

    levip I Love microskiff.com!

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    yeah i do that ... but when im trailering it the new etecs dont have a travel lock so i jack the jackplate all the way up and trim the motor all the way down - saves the seals in the hydraulics...

    read that thread pretty informative but my boat tends to run bow down due the the upward angle of the pad seems like the more weight i put forward the faster she goes.... that day i had three 200lb guys sitting on the back of the casting platform and i was at the helm running 32mph with 2 100 lb coolers, one behind the console seat and one in front of the console seat took it out friday and with my two buddies standing next to the console shed only go 30 .... damn things seems to be weight placement sensitive as hell - i know its got more top end somewhere