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  1. #1
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    I thought dealers didn't overpower boats.

    This is rated for a 90. On sale with a 150 on the back. I bet it's exciting to run https://www.tycoonmotorsports.com/de...=xNewInventory
    Last edited by rwortman; 07-18-2019 at 01:59 AM.

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    #2
    Linky no worky

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    #3

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    #4
    Thanks. I fixed the original link. I didn't see that the link button was inserting a second http://

  5. Member delee36's Avatar
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    #5
    Someone used the generic calculator to figure HP. Sample found here: http://newboatbuilders.com/pages/hp.html this is a simplified version of the calc put out by the coast guard.
    (Length x Transom Width X 2)-90 = HP (generic calculation)

    (17.5x7x2) -90 =155

    When I ordered my boat (from Polar Kraft) I questioned the HP as well and the rep said that the website information is not what the boat placard will say. Apparently the website information uses a European calculator for this (they sell a lot of boats overseas) and it calcs motor sizes smaller than the US (or so I am told). This TX is the same exact dimensions as my old Hydra-Sport and it was rated for 150hp.
    I do not know if construction material makes a difference or not. I think it should - but I do not see any info that it does.
    My 1754SE website info shows rated for 60hp but the rep says it will take a 90hp.

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    #6
    ????

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    #7
    I just saw another manufacturers website recently (I don't remember for sure, possibly Xpress). The specs for one of the models had a different max HP rating if you got hydraulic steering. I think it changed from 115 to 150.

    The HP rating on this model Polar Kraft (even if 90, but for sure if 150) in the original post is quite high. Similar sized Ranger RT178 at 17' 8"/92" beam and Tracker 175 at 17' 7"/89" beam are both rated 75 HP max.
    Last edited by madmurph; 07-18-2019 at 07:30 AM.

  8. Member delee36's Avatar
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    #8
    Quote Originally Posted by madmurph View Post
    I just saw another manufacturers website recently (I don't remember for sure, possibly Xpress). The specs for one of the models had a different max HP rating if you got hydraulic steering. I think it changed from 115 to 150.

    The HP rating on this model Polar Kraft (even if 90, but for sure if 150) in the original post is quite high. Similar sized Ranger RT178 at 17' 8"/92" beam and Tracker 175 at 17' 7"/89" beam are both rated 75 HP max.
    150 seems crazy for that boat for me as well...but like I said...my hydra sport was the exact same size and took a 150.
    I asked a facebook friend just a few minutes ago (was a marine mechanic who built custom boats as well as a 150ft+ licensed captain) - he says:
    The more specific calc to size motors incorporates materials, boat weight, chine design and other hull characteristics, as well as construction style/method of the boat. So --- is that where the differences in rated motors come from?

    I do not know - it seems confusing.
    Maybe call PK and see what size motor they say this boat will handle.

  9. Member
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    #9
    My old Stratos was about that size and took a 150 too but it was a glass boat, a pad V hull and a lot heavier. My VT-17 is the same size too and rated for a 75. The new Evinrude G2 150 is only 30 pounds heavier but I would be pretty cautious about powering my boat with it. Ratings are a bit hard to figure out. The Crestliner vt 18 is rated for a 115 and it is basically an extended VT-17. Hull thickness and beam are the same. Same for the VT-19 and it is rated for a 150. Same hull thickness and beam. I bet all three have the exact same transom. Maybe it has to do with stability at the speed the boat will be capable of and the longer hulls are more stable and slower with the same motor. That Suzuki on there is a pretty heavy motor too. Wonder how low the back is when it's sitting in the water.

  10. Member Skeeterbait's Avatar
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    #10
    There is a not to exceed formula. But I think a lot of final ratings are a debate between manufacturer's engineering and sales staff vs., manufacturer's legal staff. What will support market share vs., the level of liability the company is willing to assume. Some companies like Ranger were traditionally conservative, where some companies like Xpress were traditionally generous on ratings. Regardless, it seems like many manufacturers of aluminum boats goes thru a period of repetitive transom failures at some point in their history. Ranger, Xpress, Tracker, they have all had their share of warranty claims at times from transom issues.


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    #11
    Most of the HP ratings are to meet price points. If the RT178 was rated for 90 or 115 , how many RT188's would Ranger sell, they could rate the RT 188 for 150, but then the RT 198 would suffer. The Coast Guard formula was explained to me by a boat dealer has having to do with motor weight, not motor power.

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    #12
    Quote Originally Posted by njpaulc View Post
    Most of the HP ratings are to meet price points. If the RT178 was rated for 90 or 115 , how many RT188's would Ranger sell, they could rate the RT 188 for 150, but then the RT 198 would suffer. The Coast Guard formula was explained to me by a boat dealer has having to do with motor weight, not motor power.
    That kind of makes sense but why not raise the ratings on the whole line?

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    #13
    Quote Originally Posted by madmurph View Post
    I just saw another manufacturers website recently (I don't remember for sure, possibly Xpress). The specs for one of the models had a different max HP rating if you got hydraulic steering. I think it changed from 115 to 150.

    The HP rating on this model Polar Kraft (even if 90, but for sure if 150) in the original post is quite high. Similar sized Ranger RT178 at 17' 8"/92" beam and Tracker 175 at 17' 7"/89" beam are both rated 75 HP max.
    This is Xpress. Take my X19 for instance. Normal trim is a 150HP, add a 10" jack plate, hot foot, and hydraulic steering and it is a 200HP. Called "tournament package"
    Last edited by rolopayne; 07-18-2019 at 02:44 PM.
    2014 Xpress X-19 Pro Yammy VMAX 175 HDPI

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    #14
    That hull is rated for a 90. As mentioned, the weight of the motor is a large factor. A typical 17' .100 tin boat will have a weight limit of 390#
    2015 Ranger RT188 DC; BassCat Storage Box; Mercury Optimax 115ProXS;
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    #15
    I emailed Polar Kraft and asked them about the rating and I got no response. If I was a dealer I would not put a motor on the boat bigger than what the safety plate said. Even if the owner asked for it in writing they or their insurance company will still sue you if something bad happens because you were the person who supposed to know better.

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    #16
    Wow... a 17 ft aluminum boat with a 150 would be quite a ride. Not sure I'd want to be on it!

  17. Member
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    #17
    W/O a pad you are just wasting HP. Its only going to run so fast.
    LDS
    Larry D. Scott Retired KY Water patrol/F&W
    www.greatscottshooters.com

    2008 TRACKER TV 18 w/150 Mercury 4S
    MK Ultrex 80lb, 102 Garmin Live scope
    and a UHD93SV Garmin on the bow.
    UHD 93SV at the console.

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    #18
    A pad can make a hull go faster with the same power. Lack of a pad doesn't theoretically limit top speed. This is a picture of the back of a Donzi 41GT. Boattest.com tested this boat with 3 Merc 400's on it and it went 81mph. I don't see a pad under there. If you keep adding power to any planing hull it will keep going faster.
    Donzi 41GT.jpg
    2011 Crestliner VT-17 75 Optimax

  19. Member
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    #19
    Quote Originally Posted by rwortman View Post
    A pad can make a hull go faster with the same power. Lack of a pad doesn't theoretically limit top speed. This is a picture of the back of a Donzi 41GT. Boattest.com tested this boat with 3 Merc 400's on it and it went 81mph. I don't see a pad under there. If you keep adding power to any planing hull it will keep going faster.
    Donzi 41GT.jpg
    In my experience at some point you hit a diminishing return
    on a V boat. I owned a 20ft Crestliner w/an 80. It ran 48.
    I added a JP w/a 150 then elec trim tabs, removed the JP
    because the bow wanted to fly uncontrollably. Out of all the expense and aggravation
    I got 5 MPH increase w/almost twice the HP. Oh I did get a lot of experience changing props,engine heights
    only to find out what this type of hull wont do, and thats run fast.
    On a pad boat its all about horsepower, setup and driving skill.
    Even at that, it will stop gaining at some point. LDS
    Larry D. Scott Retired KY Water patrol/F&W
    www.greatscottshooters.com

    2008 TRACKER TV 18 w/150 Mercury 4S
    MK Ultrex 80lb, 102 Garmin Live scope
    and a UHD93SV Garmin on the bow.
    UHD 93SV at the console.

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    #20
    There is a formula for boat builders to use to get a HP rating if they do not want to test individual boats for safe operation above that. If the formula pops out 150 HP, then they also have too look at every 150 HP engine on the market and give the OK that the heaviest one would still work on the transom. The best example of this is up at the 200 HP class with the Mercury Verado 6 cylinder at way over 600 pounds. If a transom isn't designed for this much weight, then they will drop down to the next HP size that gets below the maximum allowable transom weight. Now if a manufacturer wants to rate the boat higher than the formula, they have to do enough testing to be comfortable saying that it is safe, and document this testing well enough to hold up in court that they did their due diligence should a lawsuit ever arise. Most boat builder don't want to go through this effort unless they need to go after a specific performance target for a certain boat.

    Boats above 20 feet long can be rated however manufacturers see fit with less scrutiny, so it is usually based on how much weight the transom can take.