Repowering a 54' Donzi Sportfish

Yes, we are quite familiar with chockfast. We use it all the time on big engines, gears, pumps, etc. For this small application the 3/4” plates are much easier and allow ease of future adjustments if needed.

STBD engine and gear is in the engine room. Gear was re-coupled to engine today. Photos in the engine room are not the greatest due to all the temporary shoring. Pictures are of gear, then engine, engine flying in on the ohvd crane, engine hanging in the rigging in the salon then in the engine room. The aft mount you see on the engine is only temporary. The finished mounts are on the front of engine and the gear. You can see these in the pictures.
If you look closely in the picture of the gear (only) sitting on the stringers (3rd picture) you can see a white pipe running along the inboard stringer. This is our raw water feed pipe. The old DD's have the pump and raw water inlet in the rear of the engine and so that's where the inlet valves are on the hull. We didn't want the hassle of relocating the intakes and making holes and patches in the hull. So the sea valves remain aft of the engines and we bent 2.5" CuNi pipes to feed raw water up to the pumps and intakes on the left/fwd side of the CATs. These run under the engines so will be pretty much not be seen. They are made in two pieces just in case we ever need to get them out from under the engines.
Everything seems to be fitting as expected. We now get to see that we have much more clearance around these I-6's vs the old V-12's.

The rest of the pictures for today:

I should have been more precise. The CuNi pipe is nominal 2.5", actual OD is 2.875" and it is fairly thin wall. The ID of the pipe is larger than than the ID of the intake barb on the engines. The connection between the pipe and intake barb on the engine is 3" hose. So everything feeding the engine is larger ID than the intake point ID on the engine. Sea Valves are 3". There are also very few fittings or turns.

I understand your point PB about adding another thru hull. But I can't get comfortable with that given my cored hull. The hull is rock solid around all the existing thru hulls and trying to insert something solid into the cored hull for a new location just doesn't seem like a good idea to me. Besides, there are other interfearances around the front of the engines that make 3" sea valves there problematic. I don't consider what we are doing with the raw water intake to be anything less than first class. In fact, I would bet most doing the same would simply have run a hose under the engines and called it good.

Let me clear up some things and be very precise here. The seacocks, sea valves or thru hulls, whatever you want to call them are in fact 3" (not 2.5"). The ID of the pipe we are using is 2.695". The ID of the hose barb on the engine intake connection is 2.525". The ID of 2.695" of our pipe is larger than what most 3" pipes would be, depending wall thickness of course.

Capt J - I'm aware that 3" hose is 3" ID, never said otherwise. Sorry if I suggested it was anything else but can't see where I did that. We actually used an expander to stretch the end of our CuNi pipe so a 3" (ID)hose fits over snugly.

So to be clear, everything feeding these engines has larger ID then what is required and is larger than the ID of the intake barbs. I don't think we are sacrificing anything. There is no basis to suggest impellers will wear faster nor should there be any restrictions on where the boat can go or what water temp it can operate in.

PB - the pick-ups are 3", not 2.5". And you are correct, they are installed in a non-cored area of the hull. All the thru-hulls have solid hull around them. I doubt I would have bought the boat if it didn't. Does anyone still make boats that put thru-hulls directly in the cored hull? I thought they stopped doing this a year or two after the first cored hulls came out due to water ingress into the coring around fittings ?

I appreciate all your input. We will have to agree to disagree. Pipes are not talked about in terms of ID. If that were the case you would have to have a gazillion different fittings depending on wall thickness as all the different wall thicknesses would yield different ODs and thread sizes. Nothing would screw together. Think about it now, a 3” pipe is 3” OD, the ID is driven by the wall thickness. Can you imagine if a 3” pipe had different ODs depending on all the wall thicknesses. I’ve been in the commercial Marine business for 34 years and counting. Build and Repair ships all day, every day. Every pipe I have ever seen, every drawing I look at, every Bill of Materials lists pipe by the OD and schedule (thickness)
Now, of course, flow calculations are based on ID, or the pipe size and wall thickness.
MAPISM I don’t understand your point about focusing on the 3” OD? Are you suggesting if I used a 3” schedule 160 pipe I would be fine because it is 3” OD ? That makes no sense at all to my simple mind.
Yes, a 3” sea valve has a 3” ID. But last time I checked you have to screw in a fitting, hose barb or similar to put your 3” hose on. That fitting reduces the ID.
CAPT J I did speak about ID. In fact, I gave all the exact ID sizes including, by far, the smallest which is the intake fitting from CAT on the engine.
The pipe is less than 48” long and a straight shot. Not much restriction here. I had one of our Mechanical Engineer’s take a look and they said we are fine. We are supplying more water to the intake connection on the engine than go through that fitting. CAT AGREES.
Again, I appreciate all the input and this is what the forums are all about. I will be keeping the pipes the way they are.