Transom Bracket on a 19ft boat

Discussion in 'Powerboats' started by CapeCodder, Mar 11, 2005.

  1. CapeCodder
    Joined: Nov 2004
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    Location: Ma

    CapeCodder New Member

    I am looking for some information on transom brackets.

    I am rebuilding my 19 ft CapeCodder center console (a locally made boat during the mid to late 70's) from the stringers up. It has a very stable and rugged hull. The one draw back to the boat is the low cut transom. I would like to add a transom bracket and enclose the transom. This would eliminate the problem of a constantly wet deck and free up some much needed deck space.

    My main question is what are the possible negatives to using a transom bracket on a 19 ft boat? I’ve done some research and one of the negatives mentioned was “squat” when coming off of plane. I currently have a two stroke 115hp Yamaha on the boat. Someone also mentioned some negative characteristics in a following sea?

    Presently the boat has a self bailing deck. The current transom and deck have a fair amount of water retention. I will be replacing the plywood transom and deck with foam core. The deck will be raised 1 inch. The combination of the lighter deck and transom and raising the deck one inch should offset moving the weight of the motor back.

    One person I spoke with mentioned that an Armstrong bracket was a good brand to go with. I would assume that an aluminum bracket would be considerably lighter than one manufactured from fiberglass.

    Any advice or information would be appreciated.
     
  2. woodboat
    Joined: Nov 2003
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    Location: Baltimore MD, USA

    woodboat Senior Member

    Check, but I believe the fiberglass bracket provides positive bouyancy which will help with the weight when at low speed.
     
  3. tunnels

    tunnels Previous Member

    this is an ideathat worked for me !

    I needed to do a transom replacement and get rid of the wet soggy wood so made a complete new transom with a differance !!
    Has 450mm set back ,changed motors from 20 in to 25 inch shaft , old omc 75 to a 115 yamaha so its a go fast !!. has a small deck to stand when getting in and out , no drains in the splashwell as it never gets wet . Thats my old 1975 fishing boat with a differance now there is no wood any where in the boat its 100% all glass construction !!Its and oldie but a goodie !!
     

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  4. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    Actually, if you lighten the deck and install the motor further aft it is not offsetting it but making it worse. It will move the CG even more further aft.
     
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  5. tunnels

    tunnels Previous Member

    You need a pair of good sized trim tabs if you boat squats when slowing down or traveling at slow speed . Mine does the same its why i have a 25inch shaft and mounted my motor higher up away from the water . The bracket/transom i made also has a curve to help lift the back of the boat when the stern wave hits the back of the boat if i stop quickly plus it has extra Bouyancy so its minimal the splash;)
    instead of trim tabs i intend to fit lifting strakes each side under the boat to get the hull up clear of the water and reduce wetted area . That is stage two of my modification and up date of an older hull . The boat was never intened to have a motor that big or to go that fast . :eek:
     
  6. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    A better choice is to use a longer shaft and make a taller cutout. I don't spec any short shaft outboards anymore, for the reasons stated above. The 5" difference between a short and long shaft isn't enough to upset anything, but the height change can mean the difference between taking a boarding sea or having it bounce off. Since you're redoing your transom anyway, you're correct in thinking over these types of changes.

    Another problem I see with production boats, particularly older ones, is the splash well isn't adequate. A good design splash well will absorb a boarding wave and spit it right back out. Too often I see a well, just barely big enough to let the motor tilt and too shallow to accept much more then a few quarts of water, before splashing over into the cockpit. Now, I understand the reasons they do this, mostly to offer as much cockpit space as possible, but most powerboats swamp over the stern and it doesn't have to be this way.

    As to your bracket, I'm not a fan of them on craft the size of yours, but if really bent on having one, get one with a buoyancy chamber so she isn't so bad at low speed and coming to a stop.
     
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  7. BMcF
    Joined: Mar 2007
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    Location: Maryland

    BMcF Senior Member

    I've built transom brackets (and hung/rigged the engines on them) for numerous boats in the 18'-35' range and in every case the performance was same or improved with one exception; a tendency to cavitate the prop in a high(ish) speed on-plane turn was noted on a couple of the smaller boat conversions.

    My brackets are aluminum and always encompass/include a substantial 'bouyancy box'; in some instances the boat will sit even higher at the transom with the bracket than it did without..it really depends on the hullform in each case.

    I converted a 25' deep V (Rampone) from twin inboard 140 Volvos (engines about amidship..under oversized center console) to twin Yam 150 outboards on a transom bracket. I was surpised/elated/relieved that what appeared at first glance to be a pretty radical shift of the CG aft had precious little effect on the static waterline. The take-off performance was very improved as was the top speed, the latter increasing from 28 knots to 40 knots.:eek:
     
    Last edited: Dec 8, 2011
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