Diesel I/O opinions?

rockdoc · #1 09-24-2004, 07:00 PM

What do you guys think of the Mercruiser diesel I/O's , as an option for the 23' Seacrafts? Anyone have this setup? I'm going to keep my eye out for a nice 23' Sceptre or Tsunami this winter, maybe one that needs a repower, and the diesel I/O option looks intriguing, especially in terms of range.

Steve

ScottM · #2 09-25-2004, 08:21 AM

Steve,
Although I'm not a fan of I/O's in general, I do like the diesel versions from both Mercury/Cummins and Volvo. I think you can even hitch a Yanmar up to the Merc drive too. If I remember correctly, there was a member on this site that has a Sceptre with a diesel I/O config, so if you do a search you might find him. Range is definitely the upside, plus it seems the newer diesels run quieter and smoke less than their predecessors and even their big brothers. With gas well over $2.25/gallon at most marinas, having a diesel would be nice.

Scott · #3 09-25-2004, 08:54 AM

Steve ...there was just a show on TV (shipshape maybe ??) that did a direct comparison of a diesel (jackshaft) I/O to twin out boards in a 27 Ocean master??

Needless to say the Diesel annihilated the outboards on economy ... and its overall performance was quiet amazing. They compared cruising speeds then trolling to get the comparison …. I’ll grant you it was a single diesel vs. two outboards ….but the diesel was right there with the outboards in speed (cruising speed of around 30 mph??) I would guess the outboards take it in top end ….. but of course the diesel will last a long long time !!!!

nestorpr · #4 09-25-2004, 08:41 PM

You're right, it was in Ship Shape TV last week and the diesel came out on top in every category except top end. There are a lot of great I/O diesel combinations out there and I think they're more than worth the money. This would be a great addition to any Seacraft and I highly recommend it if you can afford it! Another choice would be the 240 hp Supercharged dual rotor Mazda rotary engine from MarineRotaryPower.com. I saw a dual installation on a Bertram 25 and they looked fantastic. Each engine fits in an approximately 2 cubic foot space and weigh less than 300 lbs, that's almost a 1:1 hp to weight ratio! I would like to know more about their reliability and fuel economy, has anyone ever heard of these engines?

ScottM · #5 09-26-2004, 08:39 AM

Botapeje,
Mazda's been using the rotary engine in their RX-7/RX-8 and Millenia car models for a while now. From what I've read, their fuel economy is not great, so I assume that would transfer over to the marine environment. Otherwise, as you said, they are powerful, compact and light.

RAHIM NAHIM · #6 09-28-2004, 12:06 PM

I would look into the new CMD Cummins Mercruiser Diesel 200hp 2.8 4 cylinder engine. It's a real nice engine. It was previously a 160hp but was change to higher HP. 23SC will propably top 38mph with that engine. look into it.

R-KID · #7 09-28-2004, 08:08 PM

I have a 315 Yanmar/Bravo1 diesel ,3-4 mpg,cruise at 30-35 depending on seas,48-50 mph wide open, 79 scepter/half tower.very efficient.I don`t know how to post pics.

Ed · #8 10-13-2004, 07:11 PM

Rockdoc-

There is a charter boat (24' Rampage center console)in Nantucket that runs a diesel (Cat or Cummins, I think) to a jackshaft i/o. They tried for years to do some sort of surface piercing prop (instead of the i/o) for fishing the shallows/sandbars around Nantucket but could never get the setup right. Needless to say, the I/O option has worked pretty flawlessly for them and the boat moves.

if you have the $$$ for the initial costs of the diesel, it is definitely an option to consider.

Ed

rockdoc · #9 10-13-2004, 10:33 PM

Ed- that's Captain Tom Mlezco's "Bluedog", and I believe it's a Yanmar/ Mercruiser. I've asked my friend Nat, one of the Captains who runs the boat, and he said it's a great setup. They have quite the fleet- the 24' Rampage, two 29' Crosby Hawks, and an 18' Maritime skiff.

I should be splashing my new (1970) I/O Seafari this weekend, which will be the beginning of my I/O experience. This is a 3.0 gas engine, and I'm anxious to see how the I/O thing works out for me, as well as how a cuddy cabin works out for fishing. I'm currently fishing with a Maritime Skiff cc 18' flats boat. This winter I'm going to keep my eye out for 23' Sceptre/Tsunamis, and the diesel I/O repower option looks tempting.

By the way, Anyone know if there were any 23' Tsunami/Sceptre inboards? All I see for inboards in 23' is the CC.

Steve

sogilmore · #10 10-19-2004, 12:43 PM

I am trying to catch up with this topic. a lot of wisdom in the the replies, but I wonder about the wt of a diesel IO package.
I am going to repower my '73 23 Tsunami, it had a 454 king cobra in it (removed completely). The wt of that set up was just under 1400 lbs. It caused the boat to ride low in the aft when at rest, I refer to the discussion about wet bilges/scuppers. I am trying avoid the wt. of the big block that was there. The water in from the scupper was a big problem and a fear of mine, it would rise several inches into the boat with 3+ adults in the boat, and if everyone came aft for any reason, I worried about it getting up and over the 4" lip around the engine well.
The new Volvo w/ a small block and the new composite outdrive is of interest to me, or maybe I may scrap the whole I/O and add a bracket and go outboard....but that adds $$$$ to the repower costs over a new IO package.

Where are you with your research? Catch me up if you have gleaned any better ideas from the guys here.

-Sean