Results 1 to 13 of 13
  1. #1
    Member
    Join Date
    Dec 2017
    Location
    Homestead, FL
    Posts
    3

    17' Alumaweld H51 Yamaha V4 setup help

    Last year I bought a 1995 17' Alumaweld (old Xpress) H51 hyperlift aluminum welded pad hull boat. I'd been looking for one a while and one finally popped up at a good price and I went and checked it out and it looked solid. New carpet. No cracked welds. No hooks or dents in the bottom.

    First thing I did was put a 6" Powerlift manual jack plate and hung a 1991 3 cylinder Yamaha 90hp 2 stroke on the back. Put it in the water, and it ran 41 mph (GPS) empty with 2 guys in it. Prop shaft 2" from the pad. 17 pitch yamaha black stainless prop. I could trim the motor to the sky but not lift the bow. Was throwing a 5' to 6' rooster tail before the prop blew out.

    Next, I sold the 90 and bought a 1989 Yamaha v4 130hp 2 stroke. It came with a 23p yamaha black stainless prop. I ran it and got about 45-46mph (GPS) tops. It didnt matter if I ran the jackplate up or down, still couldn't lift the bow. I borrowed a friends 20p laser 2. Same results. It didnt matter where the 6" jackplate was, the prop would blow out before I could get any bow lift even if I dropped the plate all the way down.

    Finally, I bought a 12" setback rapid jack. With the 12" plate I've run a 21p old style quicksilver and gotten 50mph but the very best I've gotten is with a 22p laser 2 bumping 52-53 mph (GPS). It doesnt matter if I raise the plate up or down, every single prop blows out before I can lift the bow. Im currently running the laser 2 22p with the 12" plate bottomed out getting my best speed of 50-52 on any given day with an empty boat.

    I've checked the hull thoroughly for hook. It appears to be straight. Not sure if I've maxed out the capabilities of the hull or if Im doing something wrong but any input or advice would be great. All I've got hooked up currently is a water pressure gauge and a minn kota trolling motor. 2 batteries in the rear of the boat and 18 gallon fuel tank in the rear. Minimal weight in the front of the boat, life jackets, paddle, etc.

    Any help, suggestions or input would be greatly appreciated. I feel like this boat should be bumping 60 or better. TIA.

  2. Member lpugh's Avatar
    Join Date
    May 2009
    Location
    Sacramento Ca
    Posts
    5,164
    #2
    You are going have to lower the motor until you can stop the blow out, I suspect 4in or more, Take care of that first then proceed, Don't worry about bow lift so much at this point. What is the lowest P to P you can adjust to now. You may have to use different mtg holes on the motor or add some new ones on the plate. A lot more information is required to be of much help. At what trim level does it run the fastest? Do not assume that it will be at full trim up. Start at full up and watch the gps as you tweek the trim down in very small increments, It may only be tenths of a mph gains or loss. But it will determine for sure if your rig needs more lift. Getting the motor lower will help with lift as well. A little more cup on that laser may be in order as well. When yo get it right you will not need full trim up and the rooster tail will be lower. Also use this prop calculator for check prop slip with every change you make...…………….http://www.mercuryracing.com/prop-slip-calculator/
    Last edited by lpugh; 07-01-2018 at 08:58 PM.
    Thank You Leon Pugh

  3. Pat Goff
    Join Date
    Jun 2004
    Location
    Seadrift TX
    Posts
    10,942
    #3
    First you need to understand your expectations.
    How fast do you think you're supposed to go? If you're trying to match performance numbers from a fiberglass hull, you'll be disappointed.
    So, what have you learned so far?
    So far, every prop you've run is unable to maintain water contact at the trim angle you want at it's height.
    I personally like to rig iron hulls with four blade props, they disturb the water more than a glass hull, an help with handling a lot. A powertech TRO4 design would be my choice.
    Pat Goff

    Two degrees from center
    of nowhere.
    Smithwick TX.

    [SIGPIC][<a href=http://www.bbcboards.net/image.php?type=sigpic&userid=583&dateline=1498828542/SIGPIC] target=_blank>http://www.bbcboards.net/image.php?t...828542/SIGPIC]</a>

  4. Member
    Join Date
    Oct 2017
    Location
    Mobile, Alabama
    Posts
    6,551
    #4
    Almumaweld is the first clue that it is not an iron hull.

    If all of the props blow out they need more cup or lower engine height.

  5. Pat Goff
    Join Date
    Jun 2004
    Location
    Seadrift TX
    Posts
    10,942
    #5
    Dude...Really?
    We are now politically correct so I can't say something the least bit funny?
    Pat Goff

    Two degrees from center
    of nowhere.
    Smithwick TX.

    [SIGPIC][<a href=http://www.bbcboards.net/image.php?type=sigpic&userid=583&dateline=1498828542/SIGPIC] target=_blank>http://www.bbcboards.net/image.php?t...828542/SIGPIC]</a>

  6. Member
    Join Date
    Oct 2007
    Location
    Haughton, La
    Posts
    4,466
    #6
    I'd listen to Mr Goff! I've been on BBC for a long time and read a lot more than I comment. He knows stuff because he's seen stuff (and done). Realize iron, tin, aluminum in the types of rigs is a kinda of synonymous. I've seen him give a lot of good info.
    2014 Phoenix 721XP, 250 SHO, Bobs Action Jack, Dual Blades, 112 Ultrex, 2019 Lariat FX4 F150 Supercrew 4x4

  7. Member
    Join Date
    Oct 2017
    Location
    Mobile, Alabama
    Posts
    6,551
    #7
    Quote Originally Posted by pmgoffjr View Post
    Dude...Really?
    We are now politically correct so I can't say something the least bit funny?
    Sorry, didn't realize you were trying to be funny.

    I should have caught on when you said 4 blade props disturb the water more.
    Last edited by 1Holeshot; 07-03-2018 at 09:31 PM.

  8. Pat Goff
    Join Date
    Jun 2004
    Location
    Seadrift TX
    Posts
    10,942
    #8
    Metal boats disturb the water. The prop has to run in that water and a four blade is less affected.
    Pat Goff

    Two degrees from center
    of nowhere.
    Smithwick TX.

    [SIGPIC][<a href=http://www.bbcboards.net/image.php?type=sigpic&userid=583&dateline=1498828542/SIGPIC] target=_blank>http://www.bbcboards.net/image.php?t...828542/SIGPIC]</a>

  9. Member
    Join Date
    Oct 2017
    Location
    Mobile, Alabama
    Posts
    6,551
    #9
    Quote Originally Posted by pmgoffjr View Post
    Metal boats disturb the water. The prop has to run in that water and a four blade is less affected.
    That definately makes sense to me.

  10. Member
    Join Date
    Dec 2017
    Location
    Homestead, FL
    Posts
    3
    #10
    Update: best prop I've run so far that gets the boat on pad is a TURBO 1. Getting 56mph on gps. Big difference from the Lasers and other round ears I've tried. Still open to more suggestions.

  11. Banned
    Join Date
    Jul 2016
    Location
    Skiatook, Oklahoma
    Posts
    7,952
    #11
    Do what Pat said and find a 4 blade to try.

  12. Member
    Join Date
    Jun 2004
    Location
    SC
    Posts
    4,114
    #12
    IDK how many guys I've helped on the Xpress boards with H-50's and H-51's ...... especially when I had one and the many other small hyperlift hull boat models.

    The bottom line answer is you need a prop with plenty of Rake and Cup to make a 'lumnie boat run. In my experience, Lasers and all those 'Yamaha black stainless' props are junk on these hulls. The Laser doesn't have enough rake nor cup for your hull. And those black stainless Yamaha's are designed for v-hull and flat bottom boats. You want a Trophy Plus (which is a 4 blade prop). If you want nothing but the absolute top end, find yourself a Yamaha Pro Series that's made for the mid-range HP gearcases. Pitch, IDK b/c you've got that hull over-horsed and I've never seen anyone put anything bigger than a 115 on a H-51 as there was only a small time-line when Xpress would actually max out that hull with a 115. Truthfully, most H-51's are maxed at 90 .... so I have limited experience with the 115 even.

    Regardless, get yourself a Trophy Plus, or TRO4 (which is supposed to be a Trophy clone), and set the prop shaft height at 4" below the pad (make sure it's good measurements ..... level concrete, level hull and then level the prop shaft ...... then measure).

    Lastly, to really get pad hull iron boats (if I may be indulged to joke too) to run to their optimum best, you GOT to have a hydraulic jackplate. 'Lumnie boats need the prop shaft deep on these mid-HP outboards at holeshot and at mid-range and they like the prop shaft raised for optimum WOT speed. If you set the boat up for optimum speed ONLY, I can guarantee it will be a proposing 'itch! If it doesn't, then you got something else wrong and are not truly getting all that you could be.

    This is just the down-n-dirty to get you running good respectable speeds. There's a lot of other tweaks that can be made to the setup ....... but you need to walk before you run (meaning get the right prop first, set the height at 4" below, and then put a hydraulic on if you want max speed vs respectable speed).

    Good Luck!
    -391v
    '09 Ranger Z520 Silverado Edition / '09 Evinrude ETEC 250 HO
    '15 Xpress HD16DBX / Merc 59ci

  13. Member
    Join Date
    Oct 2018
    Location
    Royal,AR
    Posts
    71
    #13
    Had one with a 4 stroke yamaha on it 4" prop to pad. Tried a laser 2 22 pitch that had been worked. Put the nose up so high it chine walked terribly. Had a 115 v4 on my triton that was modified and it would do 58 mph. Still 4 inch ptp. Finding the right prop can be a nightmare. I tried over 10 different props before having one worked still wasn't what I wanted but was the best for the setup I had. If you decide to modify the 130, let me know. I still have a set of v4 heads with about 500 hours on them. I also have a set of 32 mm carbs for it and the new style float bowls that will accept the newer style jets (they dont make the old style any more). And have a 24 pitch laser 2 copy prop.
    I would think the 4 blade prop would be your best bet. Lift the whole boat instead of just the nose. Just my 2 cents.
    Nick McDaniel