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Old 13 April 2004, 18:48   #1
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Country: UK - England
Town: Poole
Make: Humber - Ocean Pro
Length: 6m +
Engine: 200 Mariner Optimax
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Tough Enough?

Having had the engine fitted to my Humber 6.3 Ocean Pro, I am starting to worry about the strength of the transom - looks an awfully big lump on that board!

Humber rate the boat at 200hp and max weight of 250kgs. The 200 Opti is 225kg.

Am I right to be concerned or are they tougher than they look?

Would it be advisable to add s-steel bracing when having the A-frame built (ala Ribtec) or shall I just stop fretting???

Your comments welcome!

Nick
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Old 13 April 2004, 19:04   #2
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Country: UK - England
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If humber are fitting the engine then you have nothing to worry about.

If Humber arn't fitting the engine you could give Andy a call just to check they dont brace the transom before they fit engines over a certain weight...
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Old 13 April 2004, 20:37   #3
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You may be right to be concerned. My Destroyer started to stress crack at the top of the knees (Johnson 150). I fitted in a 25mm marine ply section against the transom between the knees. The whole area was ground back, the ply was bedded against 3 layers of csm, laminated heavily all over and down through the well, over the knees, along the transom and onto the deck. I paid particular attention to use diolen cloth between the layers of csm around the top of the knees. The diolen is a polyester fabric which is tough and very, very much stronger than glass cloth.
The cracking started within 12 months from new. After reinforcing, I owned the boat for 6 more years with no reoccurance.

While you're at it, remove that silly piece of tube used for the bailer. Radius the corners with the biggest curve you can manage and, while doing the strengthening, laminate right through the hole. By forming a large radius, you will at least double the flow capacity of the bailer.

If you want a job doing properly........etc.

You did ask.

-----

Having said all this. From your pic, it looks as though there is a substantial extra thickness around the area at the top of the knees. Perhaps they now do it better.

I wouldn't even contemplate steel bracing. You've got to join it to the floor. What with, a couple of coach screws or a couple of bolts after you've made 2 new holes in the deck to gain acess for the nuts? Nah.
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Old 14 April 2004, 04:48   #4
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Just a word of warning to those who may feel the need to strengthen a hull - be very aware of transferring the stresses to a place in the hull that cannot handle it and creating an even bigger problem than you started with!
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Originally Posted by Zippy
When a boat looks that good who needs tubes!!!
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Old 14 April 2004, 05:23   #5
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[QUOTE=----.... You've got to join it to the floor. What with, a couple of coach screws or a couple of bolts after you've made 2 new holes in the deck to gain acess for the nuts? Nah.[/QUOTE]

Slightly off thread but these little critters allow you to fix without lots of holes in the deck .
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Old 14 April 2004, 06:59   #6
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Quote:
Originally Posted by Cookee
Just a word of warning ....- be very aware of transferring the stresses to a place in the hull that cannot handle it.....
Yeh, you're right. That's why I laminated right through the well, over the knees etc. The bumps you see at the bottom of the knees are the mahogany longits so by doing this you're locking onto the main structure as best you can.

Since I can't now edit the previous post, I gave a bit of false info., it was a bit late at night. I didn't use marine ply, I used a piece of teak and the grain was placed vertically. This was because I reconed the transom was actually flexing at the top of the knees and it required stiffening. Something else which occurred to me. The extra thickness was greater than the engine saddle could clip over so the top edge of the new section was slightly short of the top edge of the cut out and it was also chamfered to give clearance for the steering when the engine was tilted.
In your case, the cut-out is quite low and the motor saddle is mounted well above so this may not be necessary.

If anything else comes to mind I'll add it later.
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