building xf20

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MrPaul
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Re: building xf20

Post by MrPaul »

Thanks Guys. I'll keep building as planned. Looks like my wife's not going to get that mahogany bookshelf after all :D

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stickystuff
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Re: building xf20

Post by stickystuff »

Not knocking any bodys post. Just some general information.I spent many yrs. in the construction industry. Solid wood is ok for certain things. For superior strength a laminated beam is ten times stronger than a , say 2 X 12. laminated plywood has diff. layers of wood running in either side ways or horizontal grains. Some either run on diagonals. Hence this makes a laminated beam so much stronger.A solid piece of wood after exposed to the elements will actually shrink when dried out an will cause stress cracks. Just food for thought. Laminated in my eyes are the strongest way to go. :doh: :) :) :)
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MrPaul
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Re: building xf20

Post by MrPaul »

No knocking at all Ken. All advice is appreciated from everyone. I've seen your xf20 build (impressive!) and know you've got experience in building these boats. Are you saying I should ditch the mahogany and make a laminated clamping board? If so, what kind of ply should i make it out of?

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Cracker Larry
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Re: building xf20

Post by Cracker Larry »

I would, the same plywood you are building the boat out of. Plywood is much stronger than a solid board.
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MrPaul
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Re: building xf20

Post by MrPaul »

Ok. I'll build it that way. Jacques made a point of beefing up the struts that run from the stringers up the transom. Does anyone think it would be a good idea to make them a full square from the frame closest to the transom? Like in the cs23 or the phantoms.

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Re: building xf20

Post by jacquesmm »

MrPaul wrote:Ok. I'll build it that way. Jacques made a point of beefing up the struts that run from the stringers up the transom. Does anyone think it would be a good idea to make them a full square from the frame closest to the transom? Like in the cs23 or the phantoms.

Correct. They were designed for the original 25HP outboard. For anything larger, beef them up.
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Aripeka Angler
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Re: building xf20

Post by Aripeka Angler »

If you are planning to have an aft casting deck, the deck will also tape to the transom.
The deck will actually do more than the knees to stiffen up the transom.
I'm not suggesting to eliminate the knees though. Use both :wink:
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stickystuff
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Re: building xf20

Post by stickystuff »

I will give you a good example of the clamping board prob we had. On the XF I built we had stndard 1/2 ply for transom. I used a 2x8 clear fir clamping board. Also used a 3/4 " plywood horizontal all along the bottom of the clamping board as well as double knees. Now the owner wanted a 10" setback jack plate and a sixty HP Yamaha 4 stroke. The extra setback plus the weight of the engine ,Oh I forgot a power pole also which used the engine bracket mount in stead of transom bolt on mount , caused excessive weight on the transome which in the long run caused the transom to bend back and seperate the rear deck from the transom. Aluminum L shaped brackets were made and bolted down with long lag bolts (6'')down the top of theknees and through the transom with 1/2' bolts. All this and it still caused the transom to bow back out.Nida core for the decks. I would never use this stuff again. Cost to much and not worth the problems with fastening other mounts. Any thing you needed mounting on the decs had to have a plywood backing underneath.The rest of the transom above the clamping board was two layers of 3/4 marine ply. All this and still a fail. Your call. :doh:
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Re: building xf20

Post by MrPaul »

Ken,

This sounds very problematic. I was thinking a larger set back Jack plate might be a good idea to get the motor back into the water coming out of the tunnel. I currently have the entire transom made of 2 layers of 1/2" Okume plywood and still have not done the clamping board. I saw the 3/4 ply you put under the clamping board on the xf20 you built. I would have thought that would have stiffened up the transom substantially. What if I made a motor well like the phantom boats have? Do you think that would help?

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Re: building xf20

Post by stickystuff »

I think you are on the right track doubeling the transom with 2 layers of 1/2".I only used one layer. Not knowing at the time he was going to use a 10" setback J-Plate. The extra weight of the J-Plate 9approx 30" +-) plus 235# of engine weight plus the torque of the engine running. and last but not least was the power pole which used the transom engine bracket caused considerable stress on the transom, thus bending over a period of time. So, now is the time to really beef itup.Use two layers of biax fastening all the braces and brackets. With the ten in j-plate and 60HP Yamaha he only ran 29mph.Go for it. just brace it off good. Double up on the kneebraces. Thats my .02. Big ass boat. Good luck with it. You will love the big fishing platform. :D
Capt. Ken Owens

A little saw dust, a little glue, and a lot of love, and she will float.

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