New bloke needs advise with small pod design

Discussion in 'Boat Design' started by JohnBavich, Nov 17, 2015.

  1. JohnBavich
    Joined: Nov 2015
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    Location: Western Australia

    JohnBavich New Member

    Hi everyone. Great info here but I am having a problem searching for information on a pod/hull extension.

    I have a little Stacer 13.5 foot Aluminium Runabout with a 40hp Tohatsu 3 cylinder 2 stroke ob.

    She is a good little runner but possibly a little heavy on the stern. And when anchored fishing I would like a little more buoyancy and stability.

    I am thinking of fabricating a alloy pod setup. I only want about 300mm or 12 inches of extra length. This will push the motor back so it does not sit into my nice deck space.
    My questions are
    1) Should the pod follow the hull (no step up?)
    2) I think I only need a half width full height pod to mount motor, and make platforms either side for easier access from water etc .
    3) Do you need to seal the pods for to get the extra buoyancy? Or can I have a hatch through transom into the pod for storage?

    And finally what have people done with the drain bungs?

    [​IMG]
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    Cheers people

    John
     
  2. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    Heavy at the stern, as in at rest, or underway ? Podding is likely to make it worse in both instances. This is a small boat with a hefty motor for the size of it.
     
  3. JohnBavich
    Joined: Nov 2015
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    Location: Western Australia

    JohnBavich New Member

    Hi Mr Efficiency,
    Thanks for your reply, She takes a little to get on the plane but once up she goes good.
    At rest it seems a little low in the water.

    I thought a pod would add extra buoyancy?
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    You could make a couple of small pods to sit either side of the engine, that will improve it at rest. Only if you make them continuous with the bottom, will it have any effect underway. But putting the engine itself on a pod won't be any use to you, imo. If your motor has power trim (?), trim it under for better take-offs, or go in a hole with the tilt pin if it is manual tilt. If that is still no good, you could try a wedge under the engine mounting bracket.
     
  5. JohnBavich
    Joined: Nov 2015
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    Location: Western Australia

    JohnBavich New Member

    Now that's the positive info I needed. It is electric tilt trim..
    I was thinking 2 pods either side so we can stand at the transom without taking on water or listing too much. But also thought having an outboard pod as well may help.
    I think 2 small pods either side would also improve planning at low speed as the outboard would effectively be inboard a little?
    Correct me please if I am way off with the theory here.
    I still cant get my head around the outboard pod not helping though> I thought it would take a fair bit of load off the stern
     
  6. Mr Efficiency
    Joined: Oct 2010
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    Location: Australia

    Mr Efficiency Senior Member

    I took your pod idea as meaning to step the motor back further than where it is. I would not try that. That will move the centre of gravity back, both with the weight of the motor, plus the pod. A good way to get a porpoising boat. Many years ago I did something similar to what I mentioned on a small boat, but using two blocks of fairly high density polystyrene foam bolted to the transom with long threaded stainless rod, either side of the engine. I used a generously wide plate on the end of the threaded rod to stop the nut pulling through the foam when tightened. I recall being very careful to paint it with several coats of acrylic paint in case some fuel spilt into the water, and attacked it. It was a bit of a bodgie idea, but it did stop the water sloshing over the transom. But it had no contact with the water underway. If you mount something continuous with the bottom, it will alter the whole dynamic of the boat, underway, and needless to say, will need to be more robust than a slab of foam !
     

  7. hoytedow
    Joined: Sep 2009
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    Location: North of Cuba

    hoytedow Wood Butcher

    Here we call those pods squat boxes. Here is an example of how I built mine. I did put them a little too close to the motor so it bumps on sharp turns. Make sure to space them properly. Someday I will fix that with a little grinding work.

    https://www.youtube.com/watch?v=_BgLVS9CCCc

    Aluminum is outside of my skill set.
     

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