Sea Ray Sundancer 290 (1992) Outboard Re-Power

Discussion in 'Boat Design' started by Thesaintlyone, Oct 28, 2018.

  1. Thesaintlyone
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    Thesaintlyone Junior Member

    Hi there new to the forum, but long term reader. I have a 1992 Sea Ray Sundancer 290 that had its engines removed before I got her. I decided to go the outboard route for a number of reasons. and came to this forum because of the fact its more design orientated and seeking help in how to make the conversion rather than opinions on whether I should or not.

    Sorry to start blunt but I've already had plenty of people on other forums telling me its a really bad idea cause they wouldn't do it them selves, and Im hoping to get more how too advice and support if that okay.
    I also have absolutely no interest in resale value so not interested in what makes it valuable to jo bloggs 5 years down the line.

    That said my research has bought me to a number of options. in terms of the bracket or pod I am thinking either a Gill style custom built tubular design or a moulded Armstrong design.
    with the Gill tubular I am thinking of adding struts tied to the stringers for extra strength.

    either of which would sit partially hidden under the existing transom.

    My main decision is whether to go for one used 250hp outboard or a combination of two smaller say 125hp used outboards. Outboards are not as plentiful as they are in the states and it may be difficult to source two identical outboards,

    what are you guys thoughts on these ideas

    44197858_10161431479365389_1454780086866673664_n https://flic.kr/p/29nzhZ1
     
  2. Thesaintlyone
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    Thesaintlyone Junior Member

  3. Mr Efficiency
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    Mr Efficiency Senior Member

    Looks to be ~20 degree vee hull, do you know the weight of it ? I doubt 2 x 120 or 130 would be enough power, but 1 x 250 likely would. However, the dynamics of the boat would be rather different with a single 250 outboard, compared to its previous incarnation, with twin sterndrives, there being quite a gap in the weight involved, not saying that would necessarily be a big problem, but she may be more tender at rest. You have tabs to help with issues underway. Moulded pods are pretty much all the rage these days, you might like to get one that can use either single or twins, it gives more flexibility to change if needed.
     
  4. Squidly-Diddly
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    Squidly-Diddly Senior Member

    I'd go with aluminum slab welded construction like this. I just think aluminum slab most straight forward robust and versatile for project like this. Easy to cut aluminum yourself with power hand saw, etc. Versatile in that if you don't figure the stresses right the first time it will be easy to add strength. First thing I'd do is download Free Student version of Autodesk Inventor and mock it up and start playing with stresses at various thickness of materials and support struts, etc. Only thing they don't want you doing is hooking up to full paid lic version that can send data to real CAM.

    Learning curve on CAD can be little steep first time out. Check local college for starving students to CAD this if needed. But mostly I'd want a good look at exactly how the pros do it and assume they know WTF they are doing regarding stress and reinforcements etc.
    100% Aluminum Marine Structures Custom Build to your Needs http://www.custommarinewelding.com/products_engine.htm

    "
    We also have available is an installation kit to help you to mount your engine bracket onto your boat.

    Re-powering from inboards to outboards is our specialty."

    Site also has "how to measure your boat for bracket".


    To save money cut your own metal and use "L" brackets and self tapping screws to hold in place until part welded (welder will remove temp supports as he goes).

    When designing pod, consider some semi-standard size of fuel tank to fit inside. Maybe fuel tanks AND bait well.
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    Aluminium pods are popular of course, just be sure to have the face up against the hull well painted, or poultice corrosion will follow. Don't think a fuel tank in there would be good idea, though.
     
  6. Thesaintlyone
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    Thesaintlyone Junior Member

    Thanks I have considered the weight issue and will likely add extra batteries maybe even a flexible water tank as I stay on her alot. And there will be plenty of room in the now empty Engine Bay once she is cleaned up. I have seen quite a moulded pods and even found a few extra company's including Stainless Marine. The weight is given (BoatUS) at 10,900lbs but I presume that's with engines.
     
  7. Thesaintlyone
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    Thesaintlyone Junior Member

    Tbf given that there are a few companies specialising is the pods including this one I may likely just buy a pod ready to fit and just develop the design process with the company I choose, there is already the existing in built fuel tank so won't bother with another as said above would likely fit extra batteries and a flexible water tank in the now defunct engine bay to compensate the weight loss. Cheers for the reply
     
  8. Mr Efficiency
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    Mr Efficiency Senior Member

    You may need to check what the rake angle of that transom is, if you fit a pod to it, you need to end up with a rake angle of 16 or 17 degrees to the bottom of the boat, or more accurately the invisible line extension of the boat bottom, otherwise you won't get the full trim range of the engine(s).
     
  9. Thesaintlyone
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    Thesaintlyone Junior Member

    Hi thanks for the help, any idea of how I might check that or given that it's a popular production boat find out the information. I measured the distance from the transom out to the end of the integrated swim platform which was 16"
     
  10. Squidly-Diddly
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    Squidly-Diddly Senior Member

    I don't think YOUR considerable overhang was factored into the cmw.com drawings. Might need truly custom design if reduced height of attachment plate reduces its holding power. Maybe full height vertical beams on inside and through bolt to pod.


    "I might check that or given that it's a popular production boat"

    cmw.com website has page where you enter make/model, etc
     
  11. Thesaintlyone
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    Thesaintlyone Junior Member

    I am considering the possibility of running Structural supports from the pod through the transom bolted onto the stringers. I know there is a you tube video about a bayliner conversion where the tuber did the same. But one question CMW. Com???? Can't follow the link
     
  12. Thesaintlyone
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    Thesaintlyone Junior Member

    I certainly don't mind having a totally custom one built tho as long as it works
     
  13. Thesaintlyone
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    Thesaintlyone Junior Member

    And to be honest if it was easy I wouldnt be here
     
  14. Squidly-Diddly
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    Squidly-Diddly Senior Member

    sorry, my abbreviation for custommarinewelding.com in my first post.
     

  15. Mr Efficiency
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    Mr Efficiency Senior Member

    16" sounds good. With the rake, if you buy a stock pod, you want to know what the final rake angle where you bolt the motor(s) on is, and 16-17 degrees is about the number to shoot for. If there is a lesser angle on the boat transom, you may need a custom pod, or one that accommodates the lesser angle, but still gives you the 16-17 degrees on the pod where the engines bolt on. You can even use smartphones to measure angles of tilt these days, measure the bottom angle at the transom, then the transom angle, subtract, and you have the rake. Or just hold a small straight edge against the bottom, projecting past the transom, get one of those cheap little transparent plastic thingos that measure angle from a newsagent/stationer, hold it against the straight edge, and measure the angle.
     
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