Ski boat project questions

I'll be guided to a large extent by the guy who will rebuild the motor, due to his extensive experience but I expect to step the motor back 200 to 250 mm from the transom, assuming this will eliminate a transom cutout.

The fuel tank I have in mind will fit comfortably in the "channel" along the centreline (though I may have to raise the sole between the seats by 100 mm). The forward end of the tank will be roughly in line with the windscreen and therefore well forward. The attached file shows the locations of the main components (updated since last uploaded to this thread)

Cheers

Alan

 

I would be inclined to move the battery out of that location and fit it under the portside seat . Batteries don't and should never be in a place where there's the likely-hood of them getting wet and remaining wet !plus long power cables are not the best for a starter because of the possible power drop .
As far as balance goes shifting just that small amount sideways wont have any noticeable effect at all !
Don't forget to have vent holes low down and high up so there's a natural circulation of air round the battery helps keep then cool and dry and get rid of the explosive gases most batteries produce
How you going to couple the tank filler to the tank and where will you locate the filler ?? don't forget it will need a breather

I like my battery really close to the motor and tucked up under the aft deck higher than the floor so never gets any moisture and the cables are just what came with the motor !!

 

Battery location & fuel filler

Good advice and though I have already built in the battery compartment, there is room under the step to raise the battery clear of the bottom by 250 mm so I'll do that. The existing cables from the engine do reach to this point without extending them.

The fuel filler and breather will pass just behind one front seat then up to the side deck. I have not purchased the tank yet but the Scepter "topside" has the right dimensions and is reasonably priced. It looks like a copy of the Moeller tank and is $175 cheaper. Go-hard" types would probably want something bigger than 60 litres but that is just too bad.

Cheers

Alan

 

There are fillers that have the breather built in !! I have no experience of using them but would be a good idea , needs a close look at !!
Side deck wouldn't get much water on it anyway so shouldn't be a problem !!petrol in boats is dangerous at all times so double stainless steel hose clips every where and leave nothing to chance !! Bilges need ventilation at each end so fumes can get out and air can circulate naturally at all times All my boats I have done away with the drain bungs and fitted a big screw out clear port and fixed a really big capacity bilge pump right in the lowest part of the stern !! the exit pipe is always facing up so when there's water coming out its a tell tail and can see it easy !!!
Only time there ever water inside the hull is when I been fishing and hosed out the inside of the boat from end to end !!! ,then a flick of the switch and its pumped out in just a few of seconds . There's no where for water to ever get into the hull at all . no splash well as I have a 25 inch motor much higher then the usual and even going astern the water cant splash over the aft deck because its to high! with bilge pumps think what you need and double the capacity !! there is no such thing as being to big !! when and if there's a hole the amount of water coming in is huge so the pump needs to be even bigger just to keep up with the flow !!

 

Yes - as always

I have petrol cans with inbuilt breathers so I understand the principle and will adopt if available.

I also have a new 12V blower that was never installed on my last boat, so this mounted up front (well away from any petrol fumes) can be set up to operate whenever the engine runs, pushing any fumes to a vent and out to the world.

Your point about pumps is well taken and I have experience of needing one - don't ask! There is plenty of space just fwd of the transom to fit a big one.

More structural components were fitted to the interior today. These are ply well coated in epoxy and filleted in place with thickened epoxy too. I decided to change the rear seats to fore and aft along the hull sides and these butt directly onto the transom at one end and onto the midships bulkhead at the other, effectively creating large "knees" that strengthen the entire structure. With 440 gsm glass cloth over the surface of the transom. lapped onto the hull sides, it ain't going anywhere.

Cheers

Alan

 

Any progress ??

 

Progress

Yes - some progress. All the deck beams are in and I have found a supplier who will slit 140 X 25 mm Merbau into 10 mm thick strakes for the deck. This timber is much less costly than NG Rosewood and just as good, if not better. Have also acquired a 150 litre stainless fuel tank in excellent condition for just $100.

Just for a change though, I'm on the trimaran for a few days. Lovely weather if a bit chilly. Am sorting out some linkage problems with the twin rudders and might go sailing tomorrow if the weather holds.

Cheers

Alan

 

Good to hear from you and you are making progress !!. are you going to have a light colour wood between the deck planks?? could always router a groove and glue the light coloured wood in later anyway !!
Enjoy life while you can and when you get the chance !!

 

Yes D, thin strips of Paulonia that is a pleasant honey colour when varnished. These will be 10 mm wide, inserted into grooves cut with a router centrally along the 120 wide planks also into a rebate at each edge.

I think this will be a more pleasing effect than black silicone strips, about the same amount of work but far less messy to do. Bonding each strip in with thickened epoxy will be waterproof and the old trick of wiping off any excess with white vinegar before the epoxy kicks will minimise the cleanup prior to sanding.

Cheers

Alan

 

Rebuild project completed

Many of you showed interest in the earlier stages of this rebuild so I thought you might like to see the finished job. Of course, several changes were made to the original plan as the work evolved, including:

a) Reinforced the transom with multiple layers of ply - all epoxy bonded and coved, then glassed over
b) Strip planked the fore, side and well-decks with Merbau that was sliced to 12mm thick to save weight
c) Used black polyurethane between the strakes instead of the Paulownia originally planned. Sanded, sanded and then sanded before multiple coats of Danish oil, then several coats of "teak lustre")
d) Made the new windscreen in 6mm acrylic. I first made a template from a thin plastic fluoro light baffle and cut the real one to shape with an ultra-thin (1mm) angle grinder blade. This stage had worried me but actually very easy. After experimenting with pre-bending on a jig, I found it was better to screw the (then flat) screen to the centre post and bend the screen in situ using a heat gun. A couple of heavy gauge aluminium bars clamped to the acrylic kept the heat where it was needed. After bending, secured the screen with self-tapping screws into the base frame and sealed around with polyurethane.
e) Got the seats, instruments and fuel tank second hand and saved a bundle. The carpets came from Bunnings (our equivalent of Home Depot at less than half the price from the marine specialists. Got the lights and other fittings on the Internet - also way cheaper.
f)Sprayed the hull with epoxy undercoat, then 2-pack finish
g) Sold the old Mercury motor because it all got too hard to fix it from where I live and work - hope the potential buyer agrees it is better for him to select and fit any engine of his choice.
h) Bought a new cover ex Hong Kong at less than half the local price

Now let's hope I can sell it at a reasonable price to get back the materials cost and at least some of the labour - even though it really was a hobby project!

Cheers from Oz - Alan