I have a D3 in a C26 so its not a close comparison but I will post some specs and opinions.
* Performance, put the positive on the Outboard. The Yamaha 200 hp is considerably lighter then the Volvo D3 sterndrive 170hp. Yamaha 200 weighs 489lbs, Volvo D3 sterndrive 800lbs. There is some additional weight added to the R23 outboard model because of the transom motor extension bracket which will most likely make up most of the weight difference. 200hp having 30 hp more and the engine mounted further aft equates to a faster boat when comparing apple to apple boats. I do belief the Volvo diesel will stand tall at midrange planing speeds.
* Fuel economy put the positive on the Diesel. Both outboard model and diesel stern drive models will need approximately the same Hp to plane and cruise. If it takes 120 hp to plane and maintain a planning cruise speed the diesel economy will be much better. On average 1 GPH of Gas makes 12hp, 1GPH of diesel makes 18hp. If 2 R23, Gas and diesel, are running side by side same speed, using 120 hp to maintain that speed, Gas engine is burning 10 gph, diesel engine is burning 6.7gph
* longevity and reliability, there are way to many variables that go into this equation. The longevity will probably go to the diesel. Only reason I say that is the outboard needs to spin up more rpm to develop the HP. More rotational cycles equals more wear. Both engines are very close in displacement 2.8L Yamaha, 2.4L D3. Both engines are aluminum blocks with iron
sleeves. Both engines are electronically control managed, ( Reliant on electronics). Common rail diesels are not the simple diesels of pre 90's, but the hp developed in the same displacement is double.
* Safety, put the positive with the diesel. Although the Outboard is not in the bilge increasing the safety factor over a inboard mounted gas engine there is still Gasoline carried on board. The R23 has a lot of electrical devises, I assume all ABYC approved and properly installed. My biggest concern ( my opinion) with Gas on board the outboard version Rangers and Cutwaters is the poor ventilation system installed. If there was a fuel leak on board there isn't much ventilation to extract the fumes and most of that ventilation actually vents into the cockpit. The only exception is a boat with a generator but even that has limited exhaust ventilation for the size of the boats below deck area.
* Noise, The outboard wins this hands down. The newer 4 stroke outboards are quiet and well balanced engines. The diesels are not loud but have the traditional inboard sound. I notice at certain rpm's the sound from turbo and engine vibration is more noticeable so I just avoid those speeds. I personally like the traditional sound of the diesel inboard.
* Maintenance, I have owned both 4 stroke outboards and now the D3 diesel. I maintain my engines so labor is not in the equation. I always use OEM parts with the exception of oil. The Volvo parts are slightly higher in cost but not significat. Volvo diesel dealers are not nearly as abundant as Yamaha outboard dealers. I could go on about the Volvo diesel dealer network but that is another story. As far as maintenance, warranty and service work while cruising. From my experience the Yamaha would be the positive.
* Which is better? It's all up to what you want. I think if you weighed the positives and negatives you would find them right in the middle. My next boat after finishing our segmented Loop adventure will probably be an outboard powered boat again.
Dan, this is my opinions on the differences D3 compared to 200 hp Yamaha. The diesel common rail high HP small displacement engines can not be compared to the mechanical rack, simple, large displacement, low rpm, lower HP diesels from the past. The D3 under normal operating conditions is a 3000 hr engine. I think if you look at the boating market right now more larger boat manufactures are swinging toward the outboard market with the longevity of the outboards being a close comparable to the new high hp diesels.
