Aluminum hatch resize

[jkaway]

On a previous post, I was discouraged from choosing a single cylinder diesel generator and I trust this advice. Both the Nextgen 1 cylinder and the whisperpower 5 appear to receive good marks if I have no other option.

I have tried to find a way to get the Northern Lights M673LD3G to fit through my 490mm x 490mm hatch and with the help of excellent drawings provided on the Northern Lights site, I do not see a way for this to work. The oil pan and mounting plate could be removed, but the flywheel will not clear.

Are there any other options to fit the Northern Lights unit? What would be involved in opening the hatch temporarily or installing a slightly larger one? It is an aluminum deck.

[Manateeman]

What is the structure underneath. What backs up the two chainplates. Can you remove the overhead.
More info, drawings, photos please.
Mark and crew.

[jkaway]

At the moment I am at the mercy of pictures taken by those performing maintenance while I am stuck in another country. I do not have pictures of the back side but could request some. The compartment is quite spacious on the inside. Suppose that the only support structures on the backside of the hatch are angle iron under the rigging, I need less than 2" (about 45mm) more in one direction to fit the generator.


I am wondering if a cutout could be re-placed and welded without losing seal and structural integrity. The cutout would not need to go as far out as the rounded corners.

[AKA-None]

If the flywheel is the problem can’t it be removed and then replaced? Aren’t most flywheels held on with a nut and key?

[Manateeman]

Aluminum can be cut and rewelded if it’s just deck and deck beams. It’s not difficult but requires someone really experienced. Hatches come in a lot of sizes and you could increase the hatch size itself.
The issue I see is the chain plates. Lot of stress and best left alone.
Welding old aluminum takes more prep work and it helps to know exactly which type of aluminum is in the original construction.
Are you sure doing the generator in two pieces will not work? NL gensets are fantastic. Please repost photos under the deck or any drawings of the boat structure.
Mark and crew

[Paul L]

If the boat is on the hard and you have access to quality welders, how about cutting a rectangular hole in the hull and putting the genset in that way. Weld it back when installed, I've never owned a metal boat, so it would scare me, but I've seen this done on large power boats.

[Matt Johnson]

From the on deck photo, it looks like the ladder leading down into the bilge is the same as what is later shown inside. If that is the case, then the chainplates (babystays?) are attached to these longitudinal bulkheads and should be unaffected by cutting out the deck around the hatch.

But instead of just bolting in a new generic hatch, weld what you have back in place. The raised lip of the hatch often acts as a transverse stiffener and the deck may sag without it.

Matt