Thread:

79 Bahner down under! Strip back & re-paint! Over-haul during winter!

Originally Posted by cp562

Trailer looks great! Nice job. Any plans to put covers on the inside of the fenders to keep rocks from hitting the new gel coat on the hull? or are the tires to wide?

No plans for covers on the inside of fenders. Tyres are pretty wide anyway. I will however get a new boat cover made up that protects the hull from rocks being flicked up from the tow vehicle.

If gel does get chipped on inside of fenders, I have the experience now to repair it.

So the Bahner is back on the trailer, and i got stuck into ripping out the floor today. Classic story, water over the years penetrated under the between the floor and hull, and rotted out the timber. The damage i repaired previosuly from the underside of the hull makes more sense now.... the timber i could see through the damaged area in the hull was the floor! I now understand the construction of the hull a little better. Water has penerated through the damaged sustained to the hull, getting trapped between the floor and the hull. This has overall rotted the floor out.

The rotted floor came out real easy with a couple of well placed cuts on the angle grider.... Glass had delaminated from the timber, and glass had given way along the edges due to flexing over the years with people walking on it.... Came out no problems with a few litres of water waiting for me underneath.

Excuse the photos... the inside is REAL messy at the moment.... glue from old carpet over everything, debris, fibreglass..... Its going to get a tidy up thats for sure.
By the looks of it, some of the glass that holds the stringers down has also delaminated and come away form the hull.... might have to cut along the base of the stringers and reglass.....

Fortunately after initial inspection, seems to be no problems with the stringers.... But once i clean all the carpet glue off i'll be able to get a better look.
Over the next few days, i'll tidy up inside, glass in a new floor. Will also add fibreglass and re-inforement to places where required.

Gotta run and have a shower now! Playing with Fibreglass makes you itchy as hell!

Making an absolute mess!

I have begun to cut out the stringers!! Looked ok in some places, but after a deeper inspection, rot had got to them at the transom of the boat, (Some one had drilled holes through with no treatment to allow water to drain from the higher side of the stringer, down to the engine/pump area.) Stringers had sustained severe rot, they were black in colour, and very soft. Glass holding them down had also delaminated away from the hull, so i decided to start over. It was unforunate that the rot was contained to smaller areas, and the majority of the stringers were ok, but i dont want to undertake a filler repair, so have decided to cut them out, and install new stringers for piece of mind.

Used a combination of a reciprocating saw, and an angle grinder with thin blade. Did it no problems.

Half way through one side griding down the the leftover tabs and tidying up delaminated glass here and there.

Thanks to Holorinhal for his advice. Went down to a local timber place, and they have some Douglas Fir Oregon. They stock F7 grade, which should be good enough, but not kiln dried. So will have too make do. I will get it cut to size as i require. Require two pieces at 13 ft. They begin to taper in the last 4ft or so as it gets closer to the bow.

The existing stringers where 1.5" x 6". Just wondering peoples advice on stepping it up to 2" wide? This is just a pleasure lake boat, so the extra weight is not really of concern.

Also im sure it has been asked in the past, but what combo of Fibreglass matt & cloth? 4 layers & alternate? (Matt / cloth / matt / cloth?)
And what weight of material? 14oz /yd2? (450g/m2) The fibreglass thickness holding down the existing stringers was 0.27".

Not sure if I should be using Epoxy or Vinylester resin? I believe Vinylester has better adhesive properties to already cured materials?? But epoxy is the strongest. Ruled out Polyester as being the cheapest / weakest.

Again, like the flow coat, this is another learning experience for me. Any advice is appreciated.

No bulkhead in front of engine.... Probably contributed to the floor rot. I will most probably install one and flow coat it all.

Hey CP, heres an update.

Been a while since i made a post, been away on holidays on the coast.
Anyways, im back now, and have been stuck into it.

Spent alot of time on the sanding wheel on my angle grinder, followed by the DA with some 80 grit. The boat was an absolute discrace on the inside, the amount of glue used throughout the boats life was shocking. I would think it has been re-carpeted 4 times.... No amount of acetone would budge the glue, so the only way was to grind and sand it away.

Anyway, after hours and hours on the tools, i have got back to a good finish to work with. The sanding provides a smooth surface with enough bite for the new resin to bond and will also minimise air bubbles in the new layup of glass. While working on the hull i found two substancial cracks in the hull. These cracks didnt protrude all the way through the glass (Never found them while i was flowcoating the underside) so i ground them out from the inside down to the last heavy layer of woven matt in the hull, ready for a few layups of new glass. Also removed the fuel tank tabs as they were broken.

I removed all glass that was delaminated. You can see on the right hand side of the photos below the dark area that comes to a point just up from the floor. The glass in this area had delaminated away from the hull (Highlighted in red on one of the photos) so it was removed.

I have a local timber shop making the new stringers. I have provided them the detail and some drawings of what i require. 12.5ft long, 5.78" high, 1.5" thick. (Exact size of originals). I got the top edges routered to enable the glass to wrap over the top, and go them cut so they taper up towards the bow to suit the shape of the hull. They are being cut from Douglas Fir Oregon, F7 Grade. Should be ready to pick up this week.

Been sourcing other materials i need for the job. (Photo attached.) I have pack of 100 mixing sticks, 20x 1:1-5:1 mixing cups, 2 fibreglass rollers, 1kg of Cabosil (Fumed silica), and 6mm loose chopped strand. Will use the silica and loose strand to make my own thickened resin. I will use this to bed in the new stringers, and create fillet joints on either side of the new stringers where they meet the hull.

I will order the fibreglass this week. Very similar to a 1708. Buying it straight from the manufacturer NUPLEX for $6.50 per meter, compared to $22.00 that the local hardware shop is charging!! I will layup 3 - 4 layers, and alternate between (Double bias + CSM) & (Biaxial + CSM).
I have ordered 5 litres of 5:1 epoxy resin. This should arrive later in the week.

Once stringers are in, i will mock up new floor, bulk head in front of engine, new tank tabs, and most likely some gunnel supports.

Later planning to do a 1/4 flow coat job. Around the engine, jet pump, and up towards the fuel tanks. (Basically the back 1/4 from where the floor ends). This will help seal it off, and should look tidy underneath the new engine. Lots going on!

Not exactly fibreglass related, but definately some motivation to get the hull work finished.

A few photos of my blown 496ci build coming together. Thanks to Steelcomp & Straub for parts and help so far.

Also attached some engine mock up photos....

You should be proud of the labor that went into the clean-up of the hull. Looks great!!!
Looks like Steelcomp & Staub hooked you up. Keep us posted on your progress. Nice headers by the way.

Originally Posted by ItsJohny

howd fiberglassing the stringers go?

Havent quite got there yet, havent had the time. Got most of the materials i need now, stringers are in the hallway of my house. (Photos attached)

Fibreglass turned up also, much cheaper to buy per meter straight from supplier than purchase locally.

Got 2 types of glass...

1.) Stitched Double Bias (Fibres are run at a 45 degree weave to each other), with a chopped stand mat on the back. (Seen in photos with red stitching)

2.) Stitched Biaxial. (Fibres are run at a 90 degree weave to one another), with a chopped strand mat on the back. (Seen in photos with blue stitching)

Both the products i purchased are about 500g per square meter of woven stitched material + 225g per square meter of chopped strand on the back.)
Very similar to the US equivalent of 1708. (17oz of woven stitched material & 8oz chopped strand on the back)

Rolls are 1.3m wide (4.26ft). So i will be able to cut them straight down the middle and have 2 decent width strips for glassing the stringers.

I have a 4 day weekend coming this one.... so hopefully i can get started. Need to mix up some thickened resin first and bed the stringers in & create my fillet joints.

In relation to supporting the boat, some of you might be in shock but i am leaving the boat on the trailer to glass in the stingers. I feel it is far better supported on the bunks than anywhere else. I might lift the nose a little to make sure the hull is bowed to a convex shape, but not putting it on jack stands or anything like that. With a big bloke like me walking around in the hull doing glass work, it has far better support on the trailer. When i restored the trailer, i ensured the bunks where in the right position to suit the hull. The Bahner sits on it real snug.

I am using the West Systems Boat repair & maintenance manual for reference.

I already have 2.5 gallons of epoxy (pictured), but i have ordered another 2.5 which is on its way via post. Might need even more.... who knows, depends on how thirsty this glass is.

Stay tuned.

Finished off grinding, sanding today. Gave hull a clean out and mocked up stringers.

Had them in and out 20 times, sanding / making adjustments.... Happy with how they are sitting now....

Here are some photos.... The timber seperating the stingers is there only for set up. I have 2 large click grips, one at the rear, and one up under the bow.

Hope to bed them in with epoxy tomorrow....