Stretch 20
 

I've been working on the layout of my 20sf now that I've got it stripped down bare. I've got a small case of 2 foot itis and am thinking about adding in 2-3 feet just forward of the transom. I'm not expecting it to become a genuine 23 since they are significantly different boats. It just seems like an additional foot in front and a foot or two behind the console would go a long way to relieving the cramptitude.

As far as disturbing the hull design, I plan on adding a bracket so I've already departed from the original intent. Biggest opportunity for error I can figure is getting the cg located in a good spot. From a strength perspective, I'm gonna core the hullsides and probably increase the lateral cross section of the stringers either way.

Any thoughts?

I think that unless you are a boat designer, marine architect, or professional boat builder, that path is fraught with peril. Believe me, I understand the temptation to make big changes, but there are lots of potential unintended consequences. I would suggest that if a 20 doesn't have enough room, you should look for a project 23.

My $0.02
Dave

I spoke with bill potter yrs ago about putting a bracket on my 20' SF with the thought of getting more room inside and his recommendation was to just buy a 23!

I have to agree here. If a bracket alone isn't enough increase in space, then a 23 would be a better choice.

Thanks for the comments. That's the response I was expecting. Isn't there a saying about a man that refuses good advice?

Either way, I've already bought and ruined the 20 so I'm stuck with it from a sunk cost perspective.

If you are hell bent on streching the 20 you might be a lot better off doing a 24-30" stern extension than trying to splice sections in.

FWIW there is a 23 Tsunami w a bracket somewhere on ebay which might be even easier to cut cap off of.

IF your boat is a Moesly/Potter vintage hull, there are a couple of subtle features I noticed in the bottom panels when I painted the bottom on my boat that you might want to think about before you start splicing in an extension. I mentioned these features somewhere in a previous post a week or so ago, but I'll try to restate them here a little more clearly.

1. In the outer panel, if you sight aft along the chine from the front of the hull, it looks like there is a slight wedge built into about the aft 10' or so of the panel.

2. On the innermost panel, there appears to be a slight rocker in the last few feet forward of the transom.

I haven't been able to speak with Mr. Moesly to confirm the presence of these features, but they represent the type of sophistication which I believe are typical of his designs: The wedge in the outer panel would help the boat develop more stern lift to plane at low speeds, but since all planing hulls develop more lift as speed increases, I suspect that most of that outer panel is out of the waterby about 35 mph. The rocker in the innermost panel would then tend to raise the bow to get even more hull surface out of the water and reduce drag. This is a brilliant concept when you think about it . . . the wedge improves the ride at low speed when you want to slow down in rough conditions, but yet it's out of the way and doesn't hinder top speed when you want to run fast in flat water!

I believe the running angle data from the '69 Boating magazine article attached below supports this theory. Note that running angle tends to flatten out up to about 25 mph, but then starts to increase at a little over 35 mph! This test was done on an I/O powered boat with a CG located further forward than it is on an OB model, so this characteristic might be more pronounced on an OB powered boat.

IF your boat is a Tracker model, I suspect that none of this applies, because as Blue Heron noted in a previous post, there appears to be a slight hook built into his 20' Tracker model. Since they were produced later with more length and the 25" transom, they were obviously modified for heavier motors, and that probably makes them a better candidate for a bracket than the earlier models.

Would a smaller console pushed foward be easier? Just a thought.

I agree a smaller console indeed

Heck no console and just a tiller, you would have all kinds of room :D

What did you do that "ruined" it?
Dave

It's an 88' tracker. I've stripped it down to bare hull thus making it of little street value. Not a big deal in the long run but not a smart place to get out of a project either.

Never thought of a tiller. :D

Console is getting smaller for sure.

There is a pronounced wedge on my middle panel. I originally thought it was a defect.

Can someone post a picture of this "pronounced wedge" I'm reading about - not sure what this is referring to:confused:... thanks

I'll be back in my driveway in a few days if no one rogers up to it in the mean time.

Denny,
This may have been a fairly common approach for hulls like bass boats and flats skiffs that were intended to go fast, but need good manners at lower speeds. Both my Action craft and my Hewes Lappy have some hook in the outer hull panels.
Dave

Ditto My F233 Thunderbird, real wedge in the outer panel.

Yes Sir Dave, I noticed it when I put new, straight bunks on my trailer for my Bonefisher. Hummm, at first I thought it was the boards, nope the hull.

My 1975 18SF has all flat panels- no wedge, hook, or rocker.
Made it easier to add on hull extension.

I'd say go for it and try it, id cut the transom off and stretch it there. ppl do it all the time on downeast hulls so why couldn't you do it? go for it bud its only fiberglass.

That makes a lot of sense. Did they have any rocker in the center part of the hull? I wonder if Moesly was unique in that approach? Probably not, since folks have been trying to go faster in powerboats since the invention of the IC engine!