OD18 plus

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Old E.
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OD18 plus

Post by Old E. » Wed Jun 03, 2009 11:15 am

A question for Jacques (because I know he can't get enough of these :lol: ):

Disregarding plywood overages and nesting, on exactly a 10% increase in scale (up) of the OD18, would you reccomend the following:
- movement of the stringers out 1 inch (or 10%) from the centerline?
- more than 70hp?
- movement of the console/gas tank?

Anything that I didn't think of (there has to be ?

The scaling is 99% complete, and the "re-nesting" is almost complete.... going smoothly.

Thanks for the help.



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Re: OD18 plus

Post by jacquesmm » Wed Jun 03, 2009 12:46 pm

1. add a frame by respacing the frames 36" apart on average
2. use same number of stringers but respace by moving the side stringers out 10%.
3. Add one layer of glass to bottom up to 6" above DWL
4. Add one layer of tabbing all around transom and to sole/hull seam.
5. Move console 10%
6. gas tank should still go in the bow
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Old E.
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Re: OD18 plus

Post by Old E. » Wed Jun 03, 2009 1:02 pm

jacquesmm wrote: 3. Add one layer of glass to bottom up to 6" above DWL
4. Add one layer of tabbing all around transom and to sole/hull seam.
Are these an extra layer? So (as in #3) would there be 2 layers of glass on the bottom, and an extra layer (4? can't remember the orignal # off hand) at the transom?

Any thoughts on the engine?

Thanks again.

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Re: OD18 plus

Post by jacquesmm » Wed Jun 03, 2009 1:08 pm

Yes, it's an extra layer.
About the engine, the USCG rule limit the HP on a flat bottom boat and you should not have more than 50HP on an enlarged OD18.
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Re: OD18 plus

Post by TomW » Wed Jun 03, 2009 1:12 pm

Old E yes an extra layer of fiberglass on the bottom. When Jacque says tabbing that is the same as tape so an extra layer of tape on those joints. People have put up to a 115HP on there PH18's.

Tom
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Old E.
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Re: OD18 plus

Post by Old E. » Wed Jun 03, 2009 1:24 pm

Got it. Thanks.

115??? Sweet Jesus!

Edit: I re-read. You werk talking about PH18's.

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Re: OD18 plus

Post by TomW » Wed Jun 03, 2009 1:42 pm

Old E I mis-read to oops! Your OD will do fine with a 70 2st, that is what Larry has and he gets around 37-38 mph with a T-top without he would probably get a couple more. You will get a little less with your additions. Larry was going to go with a 90 but decided that he could get by with the 70. In your case the 90 might be better with the heavier/longer boat.

Tom
Last edited by TomW on Wed Jun 03, 2009 1:48 pm, edited 1 time in total.
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Old E.
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Re: OD18 plus

Post by Old E. » Wed Jun 03, 2009 1:47 pm

When it comes time, it will probably be a 4 stroke. Low 30's and I'm more than happy.

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Re: OD18 plus

Post by Cracker Larry » Wed Jun 03, 2009 4:21 pm

Very cool, lengthening (is that a word?) the OD18 8) Wish I had thought of that. It would allow enough cockpit space for fishing, and the nice leaning post/ bait station that Tom designed for me. I would move the console forward to increase cockpit space.
Any thoughts on the engine?
Thanks again.
Larry was going to go with a 90 but decided that he could get by with the 70.
I'm very glad I chose the 70. It's perfect :D This boat doesn't need a 90. I've had some experience with it now in a lot of different locations and conditions. It will run 37 mph, with a light load and smooth flat water, but I can feel she is becoming unstable at that speed. A flat bottom boat is not a speed hull, and that's fast enough for this hull.

In reality, except for my prop testing in the upper Savannah River, I've never again been in smooth flat water, or very lightly loaded :lol: In most normal kind of coastal conditions the boat is happiest running around 26-28, and becomes uncomfortable any faster than that into a chop of even 6". Running into a big chop 3'+, she is happiest around 16-18 mph. Minimum planing speed. I've got 50 hours on her now in 3 states, and have yet to find calm enough conditions to run wide open, without it being uncomfortable. The boat and the passengers both complain. I almost never exceed 5000 rpm, usually less, which is very fuel efficient for the 70.

In a following sea, this is the best handling small boat I've ever seen. It has no tendancy to broach and tracks hands free. The stern has never tried to overtake the bow like many boats do. My first encounters with a head tall following sea left me amazed. At first I'm watching every wave, wondering if it's coming over the transom, but she just rises to the occasion and keeps on tracking 8) Now I don't even look back. I can rig baits and the boat takes care of herself.

Every time I've found myself in a good following sea, we've also had the livewell full with 80 pounds of water and bait, which makes me doubly glad I didn't put a heavier engine on it. I don't think I'd be happy be less HP, but it doesn't need any more than she's got. This one's just right :wink:

One more thing E, just to throw it out there. Have you considered raising the sides any by adding a 3rd side panel? The cockpit depth in the aft section could really be a little deeper. I've almost left the boat, more than once now :oops:
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Old E.
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Re: OD18 plus

Post by Old E. » Wed Jun 03, 2009 4:31 pm

Thanks for the info.

I'm only doing the 10% increas a good friend of mine would do it for me in Rhino, and send it to a CNC machine to be cut. I think it would be too complicated otherwise. I really like low sides/shear, but the 10% overall increase includes the sides, but that 10% only amounts to like 2" or so (We measured last night, but I can't remember the exact differnce).

I knew you liked you 70hp, and I know mine will be a little somewhat heavier, so I was thinking about a 70hp and hopoin I didn't need an 80. I almost always run in the low 20's even on a v hull boat. I would imagine the OD in high 30's would be scary, but would like to have some power to get up and going quick (hole shot, if you will).

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