Heavy engine box

[hetek]

I like the seat idea. Very slick. Hey, I still have the bench seat from my A27FC. Hmmm…

If I were to cut the box I would use a right angle grinder with a thin cutoff disc, like 1/16” thin. Very dusty but quick and, imo, easier to get a straight line than a jig saw. I have a tendency to waver too much from the line with a jig saw on straight cuts. Almost no chance of chipping gel coat with the grinder too.

Use what you’re most comfortable with. A metal cutting blade for the jig saw if that’s your choice (as opposed to a wood blade). The scoring idea sounds like it would help prevent chipping.

I took off an outer skin on a 1977 24’ Penn Yan’s transom (to repair balsa core rot) with the grinder/disc method.

[hetek]

Here’s a picture!

51C29385-6D56-4DB2-8455-8722684685C9.jpeg

I used the yellow DeWalt for the transom job.
The air grinder with the cutoff disc would work too. A Formica scoring tool like WillieC mentioned is at bottom.

Now I gotta get my tools off the kitchen counter before my wife gets home!

[DesertAlbin736]

At least you have the option of partially opening the box without too much gymnastics to check oil, etc. On the early pre-de luxe full displacement hull version one has to a) unless you've modified the seat to a fold up like dkirsop did you have remove the driver seat completely & set aside on top of the aft cabin deck or elsewhere out of the way, b) swing open the hinged panel in the forward cabin bulkhead (because in the early models the box protrudes 4 inches or so into the main cabin), remove the first floorboard panel aft of the engine (because of the stepped design originally made to accommodate the 2 cyl AD21 engine), c) undo the tiedown latches at the front of the box, and finally d) lift the box up which is hinged at the back end. Conversely one good thing about that is you can easily access the front of the engine (alternator, fan belts, raw water pump) from inside the front cabin.

In this photo you can see the stepped design of the early pattern engine box.

DSCN3673.JPG

With the box opened up you get this. Note that the stepped box necessitated mounting the new engine as far forward as possible, which also allowed room to add the "Aqua Drive" thrust bearing/DV joint coupling. That makes for very quiet & almost vibration free running even at 2,400 RPM. The main drawback to a 24 HP engine propelling a full displacement hull is that top speed is limited to 6.5 knots.

DSCN3674.JPG

La Dolce Vita was repowered by previous owners with a Yanmar 3GM30F which has its oil dipstick located on the starboard side of the engine. So said previous owners cut in an inspection opening on top of the box like this. My engine instrument panels only has idiot lights, no actual gauges, so I can check engine temps by opening this inspection port & aiming a laser thermometer at the heat exchanger.

DSCN3424.JPG

They took the part that was cut out & glued a piece of marine teak veneer plywood to it so it could be dropped back in place. The antifreeze HX expansion tank is placed outside of the engine box so it can be checked & topped off as needed without opening up the whole box. Also shows how part of the engine box extends into the main cabin. Shifting the engine box a few inches aft to eliminate the need for the swing panel in the bulkhead is one of the main differences between pre-1972 & later models. Note that the part of the box that's above the cockpit floor ends even with the front end of the starboard bench seat. This photo was part of the documentation of a project to install a 20 gallon holding tank for the marine head which necessitated relocating the batteries to make room for it.

[DesertAlbin736]

I used the yellow DeWalt for the transom job.
The air grinder with the cutoff disc would work too. A Formica scoring tool like WillieC mentioned is at bottom.

I used a similar 4" pneumatic angle grinder to make inspection plates for my recent fuel tank overhaul project

20221107_111308.jpg

.