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  1. #1
    Member AussieJoe's Avatar
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    2006 285pro xl - speed issue

    Hi guys,

    im after some ideas because I'm all out.

    Last yest when i first got my 285pro XL with a 175 merc opti I was pulling 65mph just me, half fuel and a little water in the well at 5650 rpm. I haven't changed anything in the set up and am now only getting 55mph. Trying to rectify the issue have recently changed reed Valvues, didn't see much difference, maybe 2 mph or so. Have also done al the normal servicing that you should do to keep the opti in good health. Last week I blew a compressor and thought that might have been the issue and that for a while that maybe the compressor hadn't been performing well but the brand new compressor didn't change anything. I'm still getting 5650 rpm, trim is good, water pressure is good, everything I can see tells me I shouldn't be only getting 55mph that it should be higher. I should add that when plugged into the computer, there are no faults, no issues with injectors and the motor runs smoothly as it ever has.

    I also Havent hit anything in the hull, there ar no more scratches then when I got it(there are a heap but nothing that would warrant a 10mph drop in speed).

    Can an anyone give me some ideas to? because I'm fresh out and frustrated.

    Regards,

    joe
    Joe Allan
    Nitro Z7 Mercury Optimax 150hp Lowrance Ghost Simrad NSS Evo 3s
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  2. Natalie Gulbis tdt91's Avatar
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    #2
    What time of year did you get the boat last year? Did it run 65 all year last year or don't you know? How old is the prop? Have you checked for leaks that may be seeping into the flotation foam adding weight to your hull? Are your getting the MPH with a Speedo or GPS? (then and now)
    Props can wear out slowing you down. It sounds like the motor is healthy so I think it's not the motor it's self.
    Post up anything different now from the time you are comparing it too.
    2000 Javelin Renegade 20 DC.
    Strong men create easy times, Easy times create weak men & weak men create hard times. Sheikh Rashid bin Saeed Al Maktoum
    In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.
    In 2015 18-20 year old's need safe zones so people don't hurt their feelings. "Author Unknown"
    In 2021 18-40 year old's want to and work to cancel you out if you have a different opinion.

  3. Member AussieJoe's Avatar
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    #3
    Quote Originally Posted by tdt91 View Post
    What time of year did you get the boat last year? Did it run 65 all year last year or don't you know? How old is the prop? Have you checked for leaks that may be seeping into the flotation foam adding weight to your hull? Are your getting the MPH with a Speedo or GPS? (then and now)
    Props can wear out slowing you down. It sounds like the motor is healthy so I think it's not the motor it's self.
    Post up anything different now from the time you are comparing it too.
    It was running that speed for 6 months. Here is Australia where I live, there isn't a huge shift in temp between the seasons. I have changed props, gone to exact same specs(just actually a different prop) which is a 25 tempest as well as a 25 fury and the performance was similar in speed but handled a little different. Speed is on GPS and rpm is on digital smart craft.

    Haven't checked for leaks, only could be through the rub rail/join of top and bottom cap I guess if there is one. Boat is stored inside always so it couldn't get anything other the from while actually out on the water.
    Joe Allan
    Nitro Z7 Mercury Optimax 150hp Lowrance Ghost Simrad NSS Evo 3s
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  4. Member
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    #4
    So, the RPM is the same, but speed has dropped?
    If RPM is the same but speed has dropped, the prop has issues, the motor isn’t level ( they have been known to move on that vintage hull) , or you have a lot more weight in the boat.
    Even if it looks perfect, a prop can have issues. I had a spotless T1 that Mark built and I smacked a stump and put one blade out of pitch, but did not leave a mark the blade at all. Just made it run like crap.

  5. Natalie Gulbis tdt91's Avatar
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    #5
    Yep, there you go, you changed props. You either need to have what you currently have worked by a real pro or go get a new prop so you know where your at to start with.
    2000 Javelin Renegade 20 DC.
    Strong men create easy times, Easy times create weak men & weak men create hard times. Sheikh Rashid bin Saeed Al Maktoum
    In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.
    In 2015 18-20 year old's need safe zones so people don't hurt their feelings. "Author Unknown"
    In 2021 18-40 year old's want to and work to cancel you out if you have a different opinion.

  6. Member AussieJoe's Avatar
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    #6
    Quote Originally Posted by tdt91 View Post
    Yep, there you go, you changed props. You either need to have what you currently have worked by a real pro or go get a new prop so you know where your at to start with.
    No prop isn't the issue, I have used 2 X different tempest 25's and also a 25 Fury. The tempest 25 is what was getting the best speed so when I slowed I tried another 25 tempest, nothing changed, and with the fury it's about 1 mph difference
    Joe Allan
    Nitro Z7 Mercury Optimax 150hp Lowrance Ghost Simrad NSS Evo 3s
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  7. Member AussieJoe's Avatar
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    #7
    Quote Originally Posted by 201pro View Post
    So, the RPM is the same, but speed has dropped?
    If RPM is the same but speed has dropped, the prop has issues, the motor isn’t level ( they have been known to move on that vintage hull) , or you have a lot more weight in the boat.
    Even if it looks perfect, a prop can have issues. I had a spotless T1 that Mark built and I smacked a stump and put one blade out of pitch, but did not leave a mark the blade at all. Just made it run like crap.
    curious what you mean by the motor isn't level? I have a 6 inch TH marine manual jack plate, you think it may be worth checking this hasn't moved up/down one side under load or even buckled slightly?
    Joe Allan
    Nitro Z7 Mercury Optimax 150hp Lowrance Ghost Simrad NSS Evo 3s
    Proudly Supported by: Gamakatsu/Majorcraft/Fuji/Kershaw/Samurai/Atomic

  8. Natalie Gulbis tdt91's Avatar
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    #8
    Is the other 25 Tempest and 25 Fury new? If not then you don't know what you have, they can look great but be out and run like crap.
    Good luck!!!
    2000 Javelin Renegade 20 DC.
    Strong men create easy times, Easy times create weak men & weak men create hard times. Sheikh Rashid bin Saeed Al Maktoum
    In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.
    In 2015 18-20 year old's need safe zones so people don't hurt their feelings. "Author Unknown"
    In 2021 18-40 year old's want to and work to cancel you out if you have a different opinion.

  9. Member AussieJoe's Avatar
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    #9
    Quote Originally Posted by tdt91 View Post
    Is the other 25 Tempest and 25 Fury new? If not then you don't know what you have, they can look great but be out and run like crap.
    Good luck!!!
    Yes tempest was new and the fury had been blueprinted.
    Joe Allan
    Nitro Z7 Mercury Optimax 150hp Lowrance Ghost Simrad NSS Evo 3s
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  10. Member AussieJoe's Avatar
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    #10
    Quote Originally Posted by tdt91 View Post
    What time of year did you get the boat last year? Did it run 65 all year last year or don't you know? How old is the prop? Have you checked for leaks that may be seeping into the flotation foam adding weight to your hull? Are your getting the MPH with a Speedo or GPS? (then and now)
    Props can wear out slowing you down. It sounds like the motor is healthy so I think it's not the motor it's self.
    Post up anything different now from the time you are comparing it too.
    Where would the best place to start investing the possibility of a leak and water in the floatation foam and hull etc?
    Joe Allan
    Nitro Z7 Mercury Optimax 150hp Lowrance Ghost Simrad NSS Evo 3s
    Proudly Supported by: Gamakatsu/Majorcraft/Fuji/Kershaw/Samurai/Atomic

  11. Member 76Champ's Avatar
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    #11
    I'd go weigh the boat on scales first before drilling holes. 10mph loss would be ALOT of weight
    -Justin
    2006 Stratos 294 - 200 Merc Optimax

  12. Member AussieJoe's Avatar
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    #12
    Quote Originally Posted by 76Champ View Post
    I'd go weigh the boat on scales first before drilling holes. 10mph loss would be ALOT of weight
    I agree, it's a huge amount of water to make up that much lost speed.
    Joe Allan
    Nitro Z7 Mercury Optimax 150hp Lowrance Ghost Simrad NSS Evo 3s
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  13. Natalie Gulbis tdt91's Avatar
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    #13
    A common place is separation between the top cap and hull on the Aft of the boat. You will generally see a gap in the sealant when you look under the rub rail.
    2000 Javelin Renegade 20 DC.
    Strong men create easy times, Easy times create weak men & weak men create hard times. Sheikh Rashid bin Saeed Al Maktoum
    In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.
    In 2015 18-20 year old's need safe zones so people don't hurt their feelings. "Author Unknown"
    In 2021 18-40 year old's want to and work to cancel you out if you have a different opinion.

  14. Member AussieJoe's Avatar
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    #14
    Quote Originally Posted by tdt91 View Post
    A common place is separation between the top cap and hull on the Aft of the boat. You will generally see a gap in the sealant when you look under the rub rail.
    I did find a spot where there was separation between top and bottom cap. Only a small section but I guess a lot of water could get through. Now the fun part starts, how to work out if there is loads of apwater in there!
    Joe Allan
    Nitro Z7 Mercury Optimax 150hp Lowrance Ghost Simrad NSS Evo 3s
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    #15
    Aussie have you tried a different gps just to compare to your current gps ?

  16. Member AussieJoe's Avatar
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    #16
    Quote Originally Posted by Dave A View Post
    Aussie have you tried a different gps just to compare to your current gps ?
    yes I have both on my phone and the gps on the sounder. They're both reading the same speed
    Joe Allan
    Nitro Z7 Mercury Optimax 150hp Lowrance Ghost Simrad NSS Evo 3s
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  17. Member AussieJoe's Avatar
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    #17
    Quote Originally Posted by tdt91 View Post
    A common place is separation between the top cap and hull on the Aft of the boat. You will generally see a gap in the sealant when you look under the rub rail.
    There is evidence of water in the floatation foam, port side area behind the fuel tank. This could get messy trying to work out 1. How to get into the area and 2. Work out how to fix the damage we're going to to cause
    Joe Allan
    Nitro Z7 Mercury Optimax 150hp Lowrance Ghost Simrad NSS Evo 3s
    Proudly Supported by: Gamakatsu/Majorcraft/Fuji/Kershaw/Samurai/Atomic

  18. Member 76Champ's Avatar
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    #18
    I would sort out where its coming from first otherwise you'll be right back in the same boat after alot of really hard work ;) #seewhatididthere

    Even if its coming in the top cap from the hulls being separated it should not have been able to get into the foam
    -Justin
    2006 Stratos 294 - 200 Merc Optimax