Outboard power ratings and the 18 Dyne

Discussion in 'Hydrodyne® Boats' started by jim, Apr 11, 2007.

  1. jim

    jim Hydrodyne 18 Specialist

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    Several members have posted their calculations of the max power for the 18. I measured my boat including the bump rail and I believe I came up with 140 hp when rounding up. I will re-do it and publish the details later although it may not be relevant since every one seems to want at least 150.

    I have read extensively about this rating and it is based solely on the length and width at the transom and is arbitrary. It does not apply to the I/O version at all, only the outboard. The 18 Dyne has demonstrated for over 40 years that it can handle big power.

    The Coast Guard claims in their rules that the limit is a recommendation and they will not issue a citation for overpowering. They will escort you to shore for overloading. The Coast Guard does say that the placard cannot say more than the calculate limit using their formula although some Dynes do just that. Several states including WI and FL think they know more than the coastguard and have made it illegal to overpower. This law is not widely enforced in FL but the pressure is on because the hot boat guys regularly over power and they regularly get people hurt down here. Most dealers will not install a motor bigger than the limit on the plate for liability reasons.

    Some of you may want to start an effort to get an exception for ski boats or at least the 18 Dyne. There are exceptions to the rule, namely multihulls and race boats. The point can be made that the boat has demonstrated that it is safe for big power when equipped with no more than a 17 inch pitch prop because the rev limiters on the modern motors will essentially limit the max speed to say 50.

    Another way to go would be to use a bump rail that would make the transom about 6' 3" and stretch the boat to 18' 11". That would raise the limit to 150 by my calculations. Either way suits me. Stretching the boat could mean a more modern looking bow and moving the helm forward for better weight distribution.

    If there is enough interest in this, I am willing to try to put an investment group together to either buy or produce the molds to be leased to Tom Miller for a very modest fee on a boat by boat basis to continue the production of the 18. Don't expect to get rich doing this or even break even.

    http://edocket.access.gpo.gov/cfr_2003/julqtr/33cfr183.53.htm


    Please try to keep your comments constructive.

    jim
     
  2. Must-Ski Motors

    Must-Ski Motors Hydrodyne 20 Specialist

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    Jim,
    I believe there is one item that is also a huge issue, that being the level flotation requirement for any boat produced under 20'.

    This is just from my recollection, but the boat must not sink while swamped with the weight equivalent to the motor, passengers and gear for 24 hours.
    Any new boat produced must be tested by USCG and meet or exceed the level flotation requirement.

    The placards that were on 18 footers for hp rating were placed there by Hydrodyne before all the NMMA and USCG rules were in effect. I've seen 18's with hp ratings of 270 and 300, but they were manufacturer plates, not USCG (yellow) rating plates. One of the coolest 18's I saw had a 1987 3.6L V8 Evinrude on it. As tall as the outboard 18 pylon is, it was not tall enough to get over that beast and had to be made taller.
     
  3. jachainskier

    jachainskier Hydrodyne 20 Specialist

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    Must-ski, Do you have any pictures of that boat with the huge evinrude? I remember when Badgerland had one in the late 80's or early 90's. They had theres on a 20ft. dyne.
     
  4. Must-Ski Motors

    Must-Ski Motors Hydrodyne 20 Specialist

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    2008 Dyna-Ski 20' Open Bow, 3.4L 250 HO
    I don't have any pics of the 18. It was owned by Allan Hutchison who drove Badgerland's triple rig for years. He still has the boat but went to a newer Ficht Evinrude.
    Don't want to hijack this thread, but a few cool pics: One has twin 115's on an 18 and one has a 150, 175 or 200.
    Here is one of the V8 on a twenty:
    [​IMG]
    Nice 18:
    [​IMG]
    Circa 1987 20 footer:
    [​IMG]
    Single 18
    [​IMG]
     
  5. jachainskier

    jachainskier Hydrodyne 20 Specialist

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    Awsome pics.
     
  6. jim

    jim Hydrodyne 18 Specialist

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    I am aware of the flotation requirements. Here is the whole magilla if you care to read it:

    http://www.access.gpo.gov/nara/cfr/waisidx_99/33cfr183_99.html

    183.220 through 183.235 are the applicable requirements.

    This is another big mystery to me. None of the new airboats built down here have any flotation in them. They are less than 20 ft and will sink like a stone. Many of them will swamp if you back right off in deep water with any load at all.

    The Mirage tunnel hull boats built in Winterhaven are 18's and have no flotation in them. None.

    My boat was built as an I/O and had foam under the rear deck, gunnel's. fore deck, and all around the tank. The motor weighed 1000 pounds. If that is possible then I would think that level flotation should be possible with a reasonably sized engine.

    jim
     
  7. Must-Ski Motors

    Must-Ski Motors Hydrodyne 20 Specialist

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    Yep, it is not the requirement that is hard to meet, but apparently anytime a boat under 20' is produced, whether new or old by a different manufacturer, it has to be tested out east by the Coast Guard. That is the pain and the expensive part. According to Skip, the USCG has really cracked down on the small builders of outboard boats.

    Several years back there was a very high profile case of a Correct Craft getting stuck in a storm and it stayed afloat while it was swamped, likely saving the owners lives. This has always been on of CC's big selling points. They put level flotation in all of their boats despite not being required to. I know for a while Malibu did not do this, not sure if they do now or not, but CC used that as a big selling point.

    Unfortunately extending the 18 may well change the handling characteristics which people really like.
     
  8. dynegreg1

    dynegreg1 King Dyner

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    My 18' that Skip built never had a card with a rating on it. I always wondered why. Interesting topic.

    Greg
     
  9. jim

    jim Hydrodyne 18 Specialist

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    I think the boat can be lengthened and not change the handling or improve it if done right.

    jim
     
  10. jim

    jim Hydrodyne 18 Specialist

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