Pros and Cons of an I/O system

[shadowrack]

I'm looking for advise here from those with similiar experience. I recently purcahsed a 23ft downeast boat with a 305GM hooked to a Volvo 280 outdrive. THe engine and outdrive appear to be in good condition but each has age. I have been hearing both good and bad about this setup. On the positive, several have said taht the fuel economy will be beneficial while others have pointed to the inherent un-reliability of the I/O design. Any opinions here? Thanks.

[shadowrack]

I probably should have added taht if I decide to remove the I/O, then I will replace with an outboard mounted on an armstrong bracket.

[Corpus Skipper]

Just my 2 cents worth, But I'd stick with the I/O, so long as the boat is not sitting in the water 24/7. I/Os are the most efficient drive choice, especially over outboard, although I haven't seen a whole lot of real world info on 4 stroke O/Bs. I believe I/Os are a bit cheaper than 4 stroke O/Bs as well. A Cummins Mercruiser or Volvo diesel I/O would be the ultimate in range/ fuel economy. Case in point, I have a 26' Chris Craft with twin Crusader 270 hp inboards, about 10,000 lbs in cruising trim, 25 kt top speed. I get about 1 nautical mpg. The guy the next slip over has a 25' Bertram with twin Cummins Mercruisers, also around 10,000 lbs, 35 kt top speed. He gets 7 nautical mpg!!!! A fella with a 28' Bertram with twin Yamaha 250s (he took out the inboards and regrets it), around 11,000 lbs, 35 kt top speed, gets 0.7 nautical mpg. Lastly, a 27' Sea Ray, about 9000 lbs with twin Mercruiser 270s will go 40 kt at 4 nautical mpg. All of these boats have flow scans and knowledgable owners, so I believe the information is fairly accurate. I've only heard folks complain about I/O reliability when they are wet slipped in salt water, they can have corrosion problems. Ones on trailers love 'em. Quiet, smooth, no smoke/fumes, great handling. Hope this helps.

[shadowrack]

Corpus -

Thanks for the reply. I like the fuel economy issues that you refer to, I am just worried about the reliability of an older Volvo outdrive. It sounds taht the outdrives that you reference in your posting are all fairly new and as such, one would expect these drives to work as designed. For now, I'm leaning in the direction that you outline though -- to keep the I/O in place -- and see what happens.

[yipster]

parts were available for a volvo sterndrive from the stone age i once had..

[Corpus Skipper]

parts were available for a volvo sterndrive from the stone age i once had..

We have plenty of parts for "classic" Volvos here Yipster. Unfortunately it seems there is less call for them than for Mercruiser parts though Haven't heard many complaints from Bravo III owners tho. Maybe they've remedied their corrosion problems? South Texas is the ultimate proving grounds with our "hypersaline" environment. I'll volunteer to test two new Cummins Mercs in my boat!