Gunwale Installation Help!!!!

[D Gobby]

I could use some advice on Fixing what I see as a unfair shape to the Gunwale I'm installing on Bart a 15' Day Sailor.

I installed the deck beams when building the frames reducing for deck thickness. I've just started to install the Gunwale on one side. With the Gunwale in place and linning up with the top of the deck beams there is a slight Hog? between frame #1 and the stem.
If I let the Gunwale lay fair the deck beam on frame #1 is about 1/2" high.
The distance between frame #1 and the stem is 44".
Forcing the Gunwale in line with the deck beam creates a don't no if this is the right term (hog) to the sheer that doesn't show in the plans.

In the opinion of the forum should I.

(a) Let the gunwale lay fair and deal with the deck beam once the boat is turned over.
(b) Raise the point where the Gunwale meets the Stem.Increasing the over all height of the sheer at the stem. Then deal with potential deck problems.
(c) Split the difference between the stem and the deck beam.

The boat is being built upside down and I have tried to explain Up,Down etc.as it refers to the boat being right side up if that make any sense.

Any and all suggestions would be appreciat'ed

Darrel

[Art Read]

A picture would help, but if I understand your problem correctly, I'd be inclined to go with the "split difference" solution, or whatever else creates the best "looking" solution. There's a reason that "old saw" about "whatever looks right, probably is..." is still around. Just don't let anybody with a tape measure anywhere near the boat after you launch! Remember also, that things may look very different once she's right side up. (Just to further muddy the waters! ;) )

[ 01-17-2003, 04:53 AM: Message edited by: Art Read ]

[SailBoatDude]

You're going to want the gunwale to run fair. Splitting the difference will leave you with the less then fair line near the bow and it'll drive you nuts. There's been a measurement error somewhere and you'll probably find it after it's turned over if you haven't found it already. Odds are that beam is a 1/2" too high and will need be reset. Since yor're too high, you have wood to cut into for the "fix" a good thing. Though, wood butcher's friend can cure a host of ills. Keep plugging, you'll find it . . .

[Tom Lathrop]

If I understand your problem correctly, this is a common problem. When the designer draws the sheer in plan and profile, it looks perfectly fair but when the boat is formed up, the sheer shows a high spot or "hog", as you call it near the bow. It has happened to me on most boats I have built and on the ones that I have designed too.

What I do and advise other builders to do is to make the sheer fair to the eye and to heck with the plans. Usually it does not require very much to be taken off to make the sheer fair and pleasing to the eye. I think it's the combination of vertical and horizontal curves in this area that make the bow seem to droop and the result looks like a high spot aft of the bow.

[ishmael]

What Tom said. It seems the problem here might order of assembly. Having installed the deck beams to the frame by measurement, you now feel stuck with that. Without seeing the plans it's hard to say, but here is a potential solution.

Remove the deck beams. Spring a light batten along the shear and play with it till it's pleasing to the eye. Cut the shear down and reinstall the beams. Do one side of the shear first; then measurements can be taken to assure the other side is very close.

Best of luck.

Jack

P.S. Take your time with this! From some angles on the bow the otherwise pleasing shear of a small boat can have the appearance of a hump.

[ 01-17-2003, 09:55 AM: Message edited by: ishmael ]

[Tom Lathrop]

Ish,

I forgot to add that this happens on boats with a lot of flair forward or fullness in plan view. In boats with fine bows, it's not usually visible. As I said, I think it may be the way the curvature sweeps off rapidly toward the bow when viewed from the side that makes the bow seem to droop.

[ishmael]

Tom,

And both of us forgot to add that this apparent hump is normal.

Al Mason probably got it pretty close, but it is assumed that some fiddling with the shear is going to happen at this stage of building.

It's actually one of the most pleasing times of building a small boat. The hull is planked and one relies on one's eye to make the shear pleasing. Just don't go at it willy nilly. Take a few days with different placements of the batten till YOU like it.

[Paul Scheuer]

A pic would help, as Art said. Is this the assembly order called for in the plans ? Before you start cutting find out what really happened. Is there a chance that the entire frame is out of shape or out of place ? I'd hate to hear you report that you repositioned the deck beam only to find out that the chine is high.

All of this speaks for a large enough shop to be able to stand back and admire/critique your work as you go.

[Mike Keers]

As Tom sez. I've seen it in nearly every boat I've ever built to plans and loftings, and this is where your eye has to be relied on rather than measurements and the plans. When it's designed in, that hump up near the bow is called 'powderhorn' sheer. Some big sportfishermen like the Rybovich's (sp?) are designed with it.

You might want to wait until the boat is flipped over so you can walk around and sight from various angles. As Ish says, you may need to remove the deck beams, which might have been better to wait to install. You almost have to have it rightside up to plane on the sheer.

Depending on construction type, you may not be able to get all the hump out, for example, in a ply boat with an inner sheer clamp, you can only take so much off by planing the top of the clamp and ply. In the end, you do the best you can, and if there's a slight hump you can't take entirely out, it won't be the first boat that shows it, fersure.

The boat I'm building now showed it in the scale model I built, adn the real boat did too, even tho I compensated for it and thought I got it out when springing the sheer clamps to the frames and forms. I got all I can out be palning the sheer, and I actually added some height up closer to the bow, in effect bringing that last bit of dip just before the stem up, rather than trying to take all the hump down. In a case like that, you might end up shimming the foremost deckbeams.

[Ian McColgin]

A good arguement for making the frames a tad high and finishing the shere with battens and a lot os squinting.

The dory Leeward (chamberlain's double ended gunning dory) looked to have such a hump but then a batten showed that the shere could sweep a tad higher amidships. Also, I realized after, I'd made the strong back a little inaccuratly and the stems angled out more than the plan resulting in a bout about 2" over planned length.

Thankfully, Mother Ocean and Leeward both forgave me.

[TomRobb]

A fair line always trumps a measurment.
And wouldn't it be easier to eyeball the line when she's right-side-up?

[D Gobby]

Thanks for all the help Folks.

This is the first boat I'm building and in hindsight putting the deck beams in while building the frames was premature.

Yeah Ishmael Al Mason got it pretty close indeed.

Everthing so far has followed the lofting perfectly so I was a little puzzled as to what was causing the hump. I rechecked and rechecked the layout,frame dim, and strongback etc.

If I adjust the Gunwale so that the deck beam at frame #1 is 1/4" high it leaves a very very slight hump.

I think I will leave the Gunwale with the deck beam slightly higher and look at things once It's turned over.

Then if I need to adjust anything it can be quickly done with a plane as there will be little material to remove.

PS Anita did you get my last e-mail with the pic showing the Stem and Keel. If not I posted two pics here on the forum. About a week ago.

I'll post more pics next week showing the Gunwale if anybody is interested.

Thank you all again for all the help.

Darrel