Outboard engine bracket 1100lb flotation. Whats it good for? Please help!

Discussion in 'Boat Design' started by clctrader, Sep 26, 2008.

  1. clctrader
    Joined: May 2006
    Posts: 21
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    Location: Miami FL

    clctrader Junior Member

    Me and a friend are making an outboard bracket with full platform. Well, my idea was to follow the lines of the boat, the V as close as possible to kind of make it like an extention of the boat. THe boat is a 23' CC and I have put lots of $ into it already, so the whole idea is to sort of make it behave like a 26' and I also do alot of spearfishing so the platform is more important to me than anything else on the boat.

    I have added some pics of a boat that kind of has a bracket that am trying to build because it sort of looks like an extention of the boat, lik the contenders have,

    To make a long story short, here are my questions;

    IF I make it with the same shape of the boat and longer than standards, say 36" of setback; will it ride like a 26' ?

    And that kind of flotation I know its good for sea tow boats, but what will it do to my 23' Mako with a 250HP yamaha in the back? will it be good or bad?

    If anyone has any comments or pictures of similar brackets, please let me know where I can see them? I am trying to get some ideas on the shape and what it will look like,


  2. Village_Idiot
    Joined: Oct 2007
    Posts: 382
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    Location: USA

    Village_Idiot Senior Member

    I'll take a crack at this, but remember that I am an Idiot and my advice is worth every penny you pay for it. Additionally, I have not stayed at a Holiday Inn Express for quite some time. And I am not an engineer! :D

    There are quite a few folks that add additional 'flotation pods' to the transom of their jon boats to either 1) help support the additional weight of newer four-stroke outboards, or 2) make up for the buoyancy lost when running a pocket tunnel hull. In these cases, the motor stays in the same position on the existing transom and they are simply adding flotation and additional planing surface to the boat. I know it's like comparing apples to oranges, but some of the concepts remain the same.

    In almost every case, boaters who have done this really tout the benefits. The back of the boat rides several inches higher and the hull planes quicker. The tricky part for some is that if the bottom of the extensions are even with the bottom of the hull, then you can't raise the bow of the boat to take on larger waves (remember, the outboard is still in the same location, with some planing surface BEHIND the motor - a side benefit of this is that it generally cures any porpoising problems). To combat this, some folks will angle the extensions up a few degrees to get their trim range back, but then they lose some of the benefits of the extra planing surface. On a larger boat, it seems to be a moot issue and the extensions can be kept even with the bottom of the boat.

    In your case, you are moving the engine back also. Therefore, you shouldn't have any issues with trimming capabilities, and should reap the benefits of a greater planing area (e.g. - longer hull). Just be certain that your 'new' transom can handle the pressures that the engine will put on it. It is definitely better to over-engineer in this area. Existing transoms have the benefit of having the sides of the hull tied in to greatly strengthen them.

    I believe the boat will also be more of a 'pig' when it comes to slow-speed handling and maneuvering. You will have more leverage for turning, but the longer hull will take some getting used to. Depending on weight distribution, you could also end up with porpoising problems, which you may have to eventually fix with trim tabs since you will be dealing with a modified hull.
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