BR17 build - fitting the floor to the boat

Anthony Huggett · 30 Oct 2011, 22:27

I've hit a slight snag and I'd appreciate some advice, please!

The floor appears to be a snug fit onto the bearers all around the boat, but doesn't meet the bearers on the CB case. It's about 6mm too high in the middle, leaving the case free (it can be wiggled from side to side, despite being stuck in the boat at the bottom). This is a combination of 3 factors - the CB case may be a little low in the hull, and the floor is definitely convex when viewed from the top, and the hull is perhaps not quite all the way down to the formers.

The floor is amazingly stiff, even my 15 stone in the centre can't persuade it to get significantly nearer its centre bearers.

I've thought of 4 things to try:

1) Try lifting the centreboard case, flexing the hull up a bit, and screw through to the bearers from the top.

2) Use a LOT of epoxy. Don't like this idea since I couldn't be sure that the seal between the CB case and the ballast tank was OK.

3) Shim the bearers with 6mm ply, including making a top for the CB case.

4) Plane away the bearers (and the floor edges). Not sure this would work since the bottom of the floor may hit the hull panel.

Any more suggestions, advice and comments welcome.

steve jones · 31 Oct 2011, 13:52

HELLO ANTHONY,

IT APPEARS TO ME THAT YOU HAVE THE OPPOSITE PROBLEM THAT I HAD.
MY FLOOR FITTED PERFECTLY, BUT THE CB CASE PROTUDED A LITTLE HIGH.
ON TURNING THE BOAT OVER AND FITTING THE KEEL I FOUND ABOUT 6mm DISCREPENCY, WHICH I FILLED IN.

THE FLOOR ON MY BOAT APPEARS FLAT. MY SUGGESTION WOULD BE TO INCREASE THE BEARERS BY 6mm.

Anthony Huggett · 31 Oct 2011, 22:25

Steve, thanks for the advice! Great to see yours coming on.
Hoping to get mine turned over before Christmas ...

Are those outer bilge strips your own modification?

Andrew Denman · 01 Nov 2011, 09:44

Hi Anthony,

Send me an email and I may be able to assist.

regards,

Andrew

steve jones · 01 Nov 2011, 16:56

Hello Anthony,

Yes those are my own modifications, I am setting the BR17 up more as a cruising boat than a racer and have built in quite a few mods. I had previously added the bilge runners on a S17, that I had built, and found them very useful at that most vunerable part of the chine. The photo is (like all my photography I'm afraid)very poor. It does not show the c/b gasket I have fitted or the brass banding around the c/b and along the keel. This attatchment might show the bilge runners more clearly, and also the fact that I have glassed up to near the gunwhale.

All the best,

Steve

Anthony Huggett · 06 Nov 2011, 19:53

Thanks to Steve for his thoughts on here, and to Andrew for his thoughts offline.

Having had a good look at the bearers I realised I hadn't taken enough off in a few places; that has brought the outside edges of the floor down to within 2mm of design position. So the front bulkhead looks like it will be OK.

The biggest problem was the floor which despite being built flat on my (rather rough concrete) garage floor, was not flat, being 6mm or so high in the middle at the widest point. I've raised the bearers on the CB case 6mm with some spare ply, and the floor is now stuck in.

steve jones · 08 Nov 2011, 17:52

It is difficult to see from the photo' , but the cb case appears flush with the floor. In my construction it protrudes about 130mm plus a bit.
My drawings show about 100mm under the hardwood capping piece.
I have a photo' with the cb case flush , and was told that design was no longer used.
Am I misreading the picture?

Your construction looks good, you are clearly not as untidy as I am!

All the best
Steve

Anthony Huggett · 09 Nov 2011, 10:41

Hi Steve,
It only looks that way because I took the photo looking straight down the slot. It protrudes 90 mm or so above the floor on mine. I've attached another photo to show this.

I think Matt tried to design it to be flush with the floor (I think he managed it on his own prototype boat which is photographed on the website) but he wasn't happy with it for some reason. Perhaps it ships water when the ballast tank is full - the water line would only be a maximum of 4 inches below the hole.

Like you I'm going to fit a gasket to the CB case (for speed!). Did you buy the one listed on the other thread? I'm assuming you just stick it on and protect it with the metal D sections?

Anthony

steve jones · 10 Nov 2011, 18:19

Hi Anthony,

I HAVE SENT YOU CONFUSING DIMENSIONS I REALISE, THE SKETCH SHOULD CLEAR THINGS UP.
I HAVE FITTED THE CB BUT NOT THE CB CAPPING . LOOKING AT THE DRAWINGS , IT APPEARS YOUR CB CASE IS NEARER THE INTENDED HEIGHT ABOVE THE FLOOR,
AND MY FLOOR IS TOO HIGH, YET ALL SEEMED TO LINE UP, HULL ETC.

THE GASKET I USED WAS STUFF I HAD LAYING AROUND AND IS THE SAME THICKNESS AS THE OUTBOARD WELL FITTING. I HAVE LEFT A SMALL GAP OF ABOUT 10mm IN THE CENTRE .THE GASKET IS GLUEDAND SCREWED UNDER THE HALF ROUND KEEL BANDS.

AT THE MOMENT I AM TEST FITTING THE FORE AND AFT DECKS, THE SEATS AND SIDE DECKS. TO WORRY ABOUT IS STEAMING THE COAMING ( I LAMINATED UP 6mm PLY ON MY S17 , BUT THIS TIME I WILL TRY DOUGLAS FIR) MY BOAT WILL HAVE ADDITIONAL WEIGHT OF ABOUT 10 kg , SO I WILL NOT BE RACING YOU!
STEVE

Anthony Huggett · 11 Nov 2011, 12:28

Steve,

If your floor is significantly high, how did you get on with the main bulkhead? Or did you have to adjust it anyway since you were stitch and gluing the top plank? I'm going for lapstrake, by the way.

With the floor in mine as shown the outer edges of the floor are more or less at design height. Because the floor isn't quite flat, I will have to shave a couple of mm off the bottom of the main bulkhead towards the centreline.

Anthony

steve jones · 11 Nov 2011, 14:09

ANTHONY

THE STRANGE THING IS THAT ALL SEEMED TO FIT. SINCE I AM INTENDING TO DECK THE FORE AND AFT DECKS ,I HAVE HAD TO MODIFY THE BULKHEADS TO ACCOMADATE. I HOPE TO CONTINUE THE DECKING THROUGH TO THE SIDE DECKS BUT AM NOT SURE OF THE ASTHECTICS YET IN TERMS OF THE PLANK WIDTHS.
THE TOP PLANK FIXING SHOULD NOT MAKE ANY DIFFERENCE TO THE INTERNAL DIMENSIONS, SINCE I ONLY CUT OFF THE BIT THAT OVERLAPS THE SECOND PLANK.
I INFILLED THE BOW CUTOUT WITH A BREST HOOK THAT WILL BE USEFUL, AT THE STERN I INFILLED WITH A KNEE TO THE TRANSOM.

SEAT SIDES AND BEARERS ALL SEEMED TO LINE WITH BOTH BULKHEADS AS WELL.

ALL THE BEST

STEVE