Attitude

Discussion in 'Stability' started by turbo2256b, Dec 3, 2013.

  1. turbo2256b
    Joined: May 2006
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    turbo2256b Junior Member

    Havent been in here for a while have a question about the attitude of my boat.
    Its an 83 33' Apache. Originaly had twin BBCs and trs drives. The engines were replaced with SBCs the transmissions were replaced with powergulides which moved the engines about a foot forward.
    Would like to here some opinions on how this might effect the attitude of the hull on plane.
     
  2. gonzo
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    gonzo Senior Member

    If you replaced old style big blocks with modern small blocks, there is a considerable difference in weight. I assume that you are asking because the boat hasn't been in the water yet. Without any calculations, I would say the difference, if any, will be minimal.
     
  3. turbo2256b
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    turbo2256b Junior Member

    Purchased the boat this way. Have run the boat a few seasons. Just woundering how reducing weight and moving the engines forward a foot in general might have effected it. Small blocks are old school carbed goodwrench crate motors. Guessing the original owner needed the big blocks for one of his race boats and installed the small blocks. The second owner installed the powergulide transmissons in place of the marine transmissions used with the TRS drives currently on the boat.
     
  4. gonzo
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    gonzo Senior Member

    Do you mean it has Chrysler Powerglide transmissions?
     
  5. turbo2256b
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    turbo2256b Junior Member

    Powergulides are 2 speed chevy transmissions. These are built like econo rail versions able to handle 1200 to 1400 HP but dont use a torqconverter
     

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  6. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Yep, Powerglide, the racers best friend. I'll assume you're hydraulic or pneumatic shifting them. Your weight concerns shouldn't be difficult or bothersome. The savings from the Mark IV's and Mercruiser legs are easily made up with the 'glide/SBC conversion. In fact, though these packages are slightly farther forward, I'll bet your CG is about the same or even in a better location now. Of course, this depends on the top speed of the boat and it's general configuration. How much HP are you sucking through those 4150's and how fast is the boat running now? Any proposing?
     
  7. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    A Freudian slip, surely ? Your mind is on other things ? :D
     
  8. turbo2256b
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    turbo2256b Junior Member

    Shifting is done through a cable. Only issue with that I believe is the arced slot the end of the shifter travels in should have been a bit deeper. Top of the shifter has a button you push to shift it its hard to hold down because it hits the bottom of the slot and has to be held too tightly to the button of the slot. Figue on taking it appart one day and make the slot a bit deeper a 1/16 to 1/8"of an inch or so should do the job. Have thought about hydraulc or pneumatic if that dosent work. Therse throttle and shifters were all hand made.
     

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  9. turbo2256b
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    turbo2256b Junior Member

    Originally was told with the big blocks back in 83 the bost ran in the mid 90s. Also been informed the hull may only have a bout 100 hours on it and current engines were gone through after only 25 hrs on them as the boat was in storage for 10 or better years. Looking up the casting numbers the crate motores could be anywere between 260 to 300 HP. When I purchased the boat the engines were all 145 cranking compression except 3 cyl were at 140. After my first season they were all 145. Figure I finished breaking them in.
    The engines are pushing this 9000lbs boat 50 55 flat water, 65 in 2'ers or more. Thinking the roughest water I have been through is 5'ers still at 65MPH in Lake Erie.
     
  10. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    That sounds about right for two mild mannered SBC's and a clean bottom. Toss in some roller rockers and you'll get a quick 20 HP+ boost (each), without having to do anything else. These crate motors respond well to good port work, topped with an intake, still leaving the internals alone, though a fatter cam also can wake them up too.

    No typo, just looking for a new wife, preferably with a fast boat . . .
     
  11. turbo2256b
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    turbo2256b Junior Member

    The engines already have roller rockers. The springs retainers all look stock. Petronic kits were installed in the Mallory dist. Mallorys are different though one the old style advance one the cheeper new style. Other than that they look the same. Previous owner installed the petronics units said it picked up 5MPH.
    Tests I have been involved with have shown roller tip rockers perty much a joke. Roller fulcrum rockers couldnt prove a HP increase (keeping factory ratio) but do decrease engine oil temps.
    I have a lot of background in engines building for performance, economy, road racing, marine, drag racing. Spent 17 years working as an engine design engineer blocks, heads, if it bolts on an engine I have designed it at one point or modified it for my use or a customers. Also as a side line worked porting heads, intakes and such at a friends head porting shop in Michigan when he got swamped.

    A pic of engine mock up for the Apaches motors.
    A pic of some porting work
     

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  12. turbo2256b
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    turbo2256b Junior Member

    First issue with the boats handling was quartering waves it was scarier than my 236 Seebold or my Sunsation Aggressor. For that matter just about any other boat I owned.
    Found the propers were rotating inward. Switched them to outward reajusted the toe. This solved that issue havent been in any condition were the boat dosent feel like your at home watching it on TV.

    The boat itself runs farly flat just about perfect much like vidios of other Apache race boats. What does have me woundering is there seems to be no bow rise at all. Dropping the tabs doown all the way is necessary to take off. Raising them to flat once up on plane to as far up as possible there is no change in the bow rise. Thinking it should have a bit more bow lift.
    Thoughts are not enough power or is it the props. They are 19" 3 blades dont remember now but they have been cut down quite a bit from 19" and also been cupped. Possibly a combo of both power and props. Realy can drop the bow withthe planes though. Any thoughts?
     
  13. PAR
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    PAR Yacht Designer/Builder

    It sounds like you have a good bottom design and balanced boat. Bow rise can be a lot of things, including prop choices, but with modern powerboat designs, you can have your cake and eat it too. By this I mean if well designed, she'll drop down to her angle of incidence (3 - 4 degrees) then she'll just getup and scoot, without any real appreciable bow rise. I designed a racer a few years ago and it took the old school drivers nearly a year to get used to the idea it would run clean, level and dry right up to the point of longitudinal instability (over 90). A good hull will just rise up, until it hits the drag wall or "drives over center" and flops back down (or barrel rolls). My admittedly quick estimate shows a 500 HP, 9,000 pound twin with 10% slip will do 50, which is right where you are and you're running level, clean and dry. Shiit damn boy, you know how many guys I know that would pay to have these results?

    On these kinds of boats, I've found the biggest gains, other then the obvious engine improvements will be had at the prop. Call Acme Prop (acmemarine.com) and see what they can do, but again, it sounds like you've got a pretty sweet ride, that's pretty close to where it should be. Don't get me wrong, there's lot of stuff you can do like, a higher drive, notching the transom, maybe some boxes, assuming you haven't done any of these things yet.
     
  14. turbo2256b
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    turbo2256b Junior Member

    Untill I install the turbo set up not changing the props as this would change up things quite a bit. Basicly now it wont do anything but cavitate attemting to take off without fully dropping the tabs (in high gear). Low gear dosent do much taking off at this point but probably will after turbos and bigger props are dialed in to get spooled up and on plane.

    Launching now with tabs down hit the throttles (usally about 3/4 throttle) and just ease up the tabs basicly keeps the 3 - 4 degrees then back off the throttles at desired speed.
    Trim the drives a bit maybe and readjust speed if needed. Drives dont do much to attitude either as I remember
     

  15. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Can you post a picture of the business end of your boat, preferably also showing the bottom configuration?
     
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