The Ford to Cummins Conversion Thread

[rustybarge]

I'd build a acrylic hatch cover with 2" deep sides, should be enough to keep the green water out! If you google 'cnc machining' ( or diy Perspex fish tanks) you can get the persex cut to the exact spec at exactly 90 deg, and dovetail joints at the corners to make it super strong. The special glue makes the joint as strong as the original.

Then just make 2" high wooden coaming around the original cut out hole, to fit inside the Perspex hatch.Bonus: you can open hatch.

 

[MYStargazer]

I'd build a acrylic hatch cover with 2" deep sides, should be enough to keep the green water out! If you google 'cnc machining' ( or diy Perspex fish tanks) you can get the persex cut to the exact spec at exactly 90 deg, and dovetail joints at the corners to make it super strong. The special glue makes the joint as strong as the original.

Then just make 2" high wooden coaming around the original cut out hole, to fit inside the Perspex hatch.Bonus: you can open hatch.

Wow! Never thought about cnc machining the acrylic. I feel a plan brewing, and possibly a Paint sketch. Want to avoid more wooden bits on the roof if I can...

 

[rustybarge]

Wow! Never thought about cnc machining the acrylic. I feel a plan brewing, and possibly a Paint sketch. Want to avoid more wooden bits on the roof if I can...

My son has just made a 'cnc cutting file' to make a new Perspex case for his desktop pc. He downloaded the software free off the internet, and he has found a company to cnc machine it; but no price as yet.

I will update you with further progress........

 

[MYStargazer]

My son has just made a 'cnc cutting file' to make a new Perspex case for his desktop pc. He downloaded the software free off the internet, and he has found a company to cnc machine it; but no price as yet.

I will update you with further progress........

Thanks - look forward to it!

Here's my first idea. The grey is stainless (I'm going to buy a TIG welder and teach myself - hopefully).

Here's my updated idea, now I know that acrylic sheet can be cnc milled and even dovetailled - I don't want it to open as that'll complicate things too much.

 

[Episode]

I post this appeal…

http://www.ybw.com/forums/showthread.php?368706-Anyone-know-this-bloke



…to no avail, but now he's turned up on the forum - welcome Nigel!



His repower thread is here http://www.ybw.com/forums/showthread.php?371173-Weymouth-32-re-power-D4-for-Perkins-HT6-354



Easily, and with plenty of room to spare all around. Height (only) was tight, but the floor may have been raised by an inch or so (just by adding battens) to accommodate the charge air coolers and air intake crossover. I’m wondering why your floors are so low. Or, maybe, your engine beds and p-brackets are more steeply angled. The original Halmatic boat plans I have feature your Perkins and a steeper shaft angle. Maybe playing with this angle (new or reinstalled p-brackets and reworked engine beds) would offer some cheaper alternatives to Volvos, new gearboxes and Aqua/Python drives…?

I had come to the same conclusion about shaft angles. I have considered new P brackets and the such but will still invoke raising the floor (and smaller dia props, not so good). Floor would be difficult and expensive to do well. Less the floor structure itself, but where it buts against the cabin furniture and other fittings. Also mean that the final step up from the cabins would be big. Ok for me but not so good for the dog

 

[penfold]

Your first scheme would be a challenge for an experienced stainless steel wrangler, not something I'd want to try to DIY, and you have twice as many leak paths. The second has legs, although getting a good seal between the acrylic and the s/s angle frame won't be fun as the acrylic has a much greater thermal expansion coefficient. Perhaps a cheaper way would be to just remove the rebate(or fill it in with CSM) and put the acrylic down onto the GRP and only have 1 leak path. Granted the s/s frame offers a lot of extra stiffness in the coachroof, but you could add an internal s/s frame to take the fastener threads.

 

[MYStargazer]

I had come to the same conclusion about shaft angles. I have considered new P brackets and the such but will still invoke raising the floor (and smaller dia props, not so good). Floor would be difficult and expensive to do well. Less the floor structure itself, but where it buts against the cabin furniture and other fittings. Also mean that the final step up from the cabins would be big. Ok for me but not so good for the dog

Yes, my props are limited to about 21" diameter IRRC.

I'm not impressed by creaky James & Caddy joinery and space solutions so I'm being quite brutal with my interior rethink.

 

[MYStargazer]

Your first scheme would be a challenge for an experienced stainless steel wrangler, not something I'd want to try to DIY, and you have twice as many leak paths. The second has legs, although getting a good seal between the acrylic and the s/s angle frame won't be fun as the acrylic has a much greater thermal expansion coefficient. Perhaps a cheaper way would be to just remove the rebate(or fill it in with CSM) and put the acrylic down onto the GRP and only have 1 leak path. Granted the s/s frame offers a lot of extra stiffness in the coachroof, but you could add an internal s/s frame to take the fastener threads.

Yes, I was wondering how concerned I should be about stiffness. Seems all good and stiff now, but that's while she's high and dry.

I'll sketch what I think you're suggesting so I'm on the right lines...

 

[MYStargazer]

Like this?

 

[rustybarge]

Like this?

http://i1177.photobucket.com/albums/x342/matrixLloyd/NewRoofPanel4.[/QUOTE]

Overlapping joint like you have illustrated is definitely the safest joint, but not very elegant.
Polycarbonate scratches the easiest, then acrylic; But You're not going to be walking on the wheelhouse roof very often anyway, except in locks on a canal.

In the end it's also the easiest to do, I'd go with that.

 

[Fantasie 19]

Overlapping joint like you have illustrated is definitely the safest joint, but not very elegant.
Polycarbonate scratches the easiest, then acrylic; But You're not going to be walking on the wheelhouse roof very often anyway, except in locks on a canal.

In the end it's also the easiest to do, I'd go with that.

That's the same way some people do replacement yacht windows as well - when they do it they bed the perspex/acrylic sheet on butyl tape for added "waterproofness".... then bolt through..... apologies of this is teaching granny etc, but don't forget that the holes also need to be slightly bigger than the bolt to allow for slight heat/cold expansion

 

[vas]

Like this?

getting better, however I personally wouldn't drill and bolt through these two materials.
I'd built an extra L shaped polywhatever to clamp and hold the acrylic sheet on the ply roof from the inside. The through bolts would be between compatible (i.e. similar) materials with close/identical expansion co-efficients and no chance of ripping/cracking the weakest apart.

BTW, are you sure the roof is single curvature (must be as it's ply, but worth checking carefully).
I mean, the roof on a side elevation is straight???


I'd prefer the strengthening and "elevation" of the acrylic to be done via a timber batten epoxied on top of the roof, creating a clean edge, and THEN have the second option of your first post with drawings. Ah, and not bother with bolting it through that way (I know it would cause issues when trying to remove the acrylic sheet)

If you're going such a route, I'd definitely search my options to lift the aft side of this cover up 4-5inches for ventilation (or remove it altogether assuming you can safely store it somewhere...)

IMHO structuraly it does close to bugger all

cheers

V.

PS. sorry don't have the time now to do some sketches, maybe later on tonight

 

[MYStargazer]

Polycarbonate scratches the easiest, then acrylic

She has been through locks, and access to the cabin roof's certainly been needed.

I'm thinking I could apply a layer of protective film - like the stuff used for stonechip protection on cars...

Or I could find out who supplies curved toughened glass to bus shelter manufacturers.

 

[MYStargazer]

butyl tape

apologies of this is teaching granny

Far from! Thanks - I'd never heard of butyl tape, other than flicking through the Screwfix catalogue and wondering what on earth it does!

 

[MYStargazer]

I'd built an extra L shaped polywhatever to clamp and hold the acrylic sheet on the ply roof from the inside. The through bolts would be between compatible (i.e. similar) materials with close/identical expansion co-efficients and no chance of ripping/cracking the weakest apart.

Thanks for the suggestion. Can't quite picture what you mean, though.

BTW, are you sure the roof is single curvature (must be as it's ply, but worth checking carefully).

The roof's GRP foam sandwich - about an inch thick overall. It looks like single curvature only, and the plans show it to be single curvature, but I should check this to be sure...

 

[rustybarge]

Maybe my idea of a big hatch cover made in acrylic, the pieces cut by Cnc machine, is looking like the best solution, And It's easy to glue a small coaming around the the hole in the roof.

Please please forgive me for mentioning 'saily' things on this thread, but something like a companionway sliding hatch in acrylic might suit very well, and it's totally waterproof......

 

[MYStargazer]

Maybe my idea of a big hatch cover made in acrylic, the pieces cut by Cnc machine, is looking like the best solution, And It's easy to glue a small coaming around the the hole in the roof.

Please please forgive me for mentioning 'saily' things on this thread, but something like a companionway sliding hatch in acrylic might suit very well, and it's totally waterproof......

It's a great idea, and I've seen this done on a new motor boat of a similar size to mine (in Spain - can't remember the brand or model) but I think making it openable is going to make it a little too complicated for me.

So I think I'll go for this solution. The orange is a moulding - preferably made from GRP(?) or some other material which can be epoxied onto gelcoat. I've no idea where to source such a moulding yet, though - especially for the corners (the acrylic sheet will have very rounded corners). The black is butyl tape, and the green is epoxy.

Thoughts on where to source the straight moulding and moulding corners gratefully received! Perhaps someone makes something suitable from aluminium?

 

[penfold]

I don't see what the orange moulding is adding, other than a water trap and perhaps making the cosmetics better.

 

[MYStargazer]

I don't see what the orange moulding is adding, other than a water trap and perhaps making the cosmetics better.

Yes - just for cosmetics. Hadn't thought about water being trapped (duurr! - thanks). I think I'll look for a profile with a much smaller overlap. If I can find a suitable profile at all...

 

[penfold]

For cosmetic trim you can get plastic quarter round beading in various sizes; that bonded onto the GRP with sika would do the job. You could also get the edge of the acrylic either chamfered or rounded over to give a more pleasing appearance without trim.