keep I/O or convert to OB.....?

:?: Hi there, Nice site. I need some advice.

I know alot about boat restoration, some fiberglas, some things about O/B's and diesels. But I know nothing about I/O's. I have skills......some anyway. And I like messing with things.

I'm looking at buying a 1982 Robalo 22 cuddy for fair-weather offshore fishing on the Gulf Coast. I'm only interested in the boat and trailer because the I/O is original OMC. It's a throwaway.

My question is whether to repower with a used/rebuilt motor and sterndrive or rebuild the transom and put on a 200 hp Yamaha OB that I have (freshly rebuilt). My understanding so far is that the I/O's are better on gas, and cheaper to rebuild/replace. The downside is weight, explosion potential, and wasted cockpit space. I could go either way. Either one is a project.

What opinions do you people have one way or the other on the two systems? One thing that stands out is that most fishermen on the coast here don't like I/O's. But I still don't know why. Suggestions would be helpful. Thanks......

 

Well B, since nobody stepped up, here goes. If the boat is to be trailered or kept on a lift, go for the I/O says I. They are a LOT more efficient than O/B or straight inboard, quieter than O/B, and you don't have that @#*!! thing sticking up in the middle of your transom, never mind the gaping hole in the transom where the engine sits, just waiting for a big wave to hit you in the stern and swamp ya. In the gulf, O/Bs are best bracket mounted IMHO. The reason no one around here likes sterndrives is because corrosion can be a big problem, especially for Mercs, if the boat is wet slipped. But if trailered or kept on a lift, and flushed EVERY time you run the boat, they're just as good as any other for longevity. You do loose a bit of cockpit space to the engine, but you can mount your fighting chair on top of the box as many Bertram 25 owners have, and I like the "coves" on either side of the transom, you can brace yourself in there with your legs and feel very secure when gaffing or wiring. One final thought, I have a 26' Chris Craft flybridge with twin Crusader 270s. The boat'll do 26 kt and cruise at 20 (I do need more pitch, will get maybe 30/24 kt). A friend has a 27' Sea Ray approximately same weight as mine, deeper V, same engines on Bravo III drives. He can do about 45 kt. and cruise at 35 while getting TWICE the fuel economy I get (1 mpg ). Just my 2 cents worth.

 

Craig,

What's I/O, O/B, IMHO, @#*!! (I can guess that one!)?????

 

What is....

I/O = Inboard/Outboard (aka (also known as) Stern Drive)
O/B = Outboard
IMHO = In My Humble Opinion

 

Thanks Fisher , now I get the discussion :idea:

 

Graig, yes our sundancer has similar data so should i be glad
a bit more expensive but those bravo III legs are pritty good, specially on a single eng setup. if ever to do 2 drives over again, i may go for a left and a right hand rotating engine with Bravo II's and single 5 blade props (was reading the new line of mercruiser 5 blade props are now 20% more efficient) and chieper as the CR props...

 

I was wondering if I'd ever get a reply; seemed like a straight-forward question.

OK Corpus. As I said I know nothing about I/O's, so what is the Bravo and why is the same size and weight boat getting much better gas mileage than you?

The boat would be trailered, so I guess that helps the I/O arguement. And the positives that you pointed out sound reasonable to me. And I must admit, even though I have the skills to convert the transom......I don't really want that project right now. Ugh!! But the problem is......: the old I/O in the boat is worthless. It's a repower. Repowering an I/O from scratch, even with remanufactured components, will get very expensive. Whereas, I already have the OB. And how much money do I want to sink into a 1982, even if it is a Robalo (strong boats). There's the dilemma.

I have recently been doing alot of studying-up on I/O's, and I now understand their inner workings much better. Having owned a large sailboat with a Volvo I/O I am familiar with heat exchangers, exhaust manifolds, risers, etc, and I know first-hand how these corrode and clog.....leading to Big Bucks!! (especially the stinkin' Volvo!!) So, old I/O's, especially someone else's, will be nothing but trouble. If I started from scratch at least I'd know what I've got and how to take care of it. But still, the cost of repowering.....Whew!! I haven't bought the boat yet so I'll think about it awhile.......

 

The costs are pretty much the same for either set up, but since you already have the O/B, maybe that's the best route, if it's a newer engine. As far as the transom work goes....I'd just plug the hole and bracket mount the engine. Quicker, easier, and above all, safer.

The Bravo is just a Mercruiser stern drive, the Bravo IIIs being the latest and greatest, with a duoprop setup. I believe the greater economy comes from a more streamlined underwater profile provided by the stern drives versus prop shafts, struts, rudders......

Sorry Dutch, sometimes I forget this is an international forum, but hey, we both learned something!

 

I/O and stern drive

Is I/O the same as a stern drive? What is the difference? I'm just not sure what these are. And, what would you say would be the best solution for a larger wet slipped saltwater, If the I/O will corrode, I think a stern drive woudl too. Are straight inboards better? That is, a mototr with a straight shaft and a prop at the end with rudder steering. I guess that is fewer metal parts in the water that the salt can get too. In the end, maybe O/B is better for a w3et slipped saltwater boat since you can pull them out of the water?

TIA

 

I/O ( inboard/outboard)... is the same as a stern drive... A bravo outdrive is a fairly cheap outdrive that will take moderate power (about 350 hp) This outdrive has a cone clutch built inside that differentiates between a top and bottom cone... hence... no transmission needed for forward or reverse... but if they start to slip... they self-destruct quite quickly. Any engine.. inboard or outboard... or one with a stern drive are all subject to corrosion if left in the salt water. They need to be back flushed or have a closed cooling system... also... you will need sacrificial anodes to keep the electrolosys in control. If the boat is small ... say 18 foot... you can tip the outboard out of the water and flush it to keep the corrosion down. Large outboards are too big to do this. The big advantage of a sterndrive is you can adjust the outdrive up or down for pushing the bow up and lessening the wetted surface... which equals faster speed.

 

'm building a 24' Ken Hankinson powercat
http://www.boatdesigns.com/cgi-bin/store/web_store.cgi?page=wildcats.html&&cart_id=8171429_25177

and I was strongly advised by another builder that outboard brackets are the way to go with this boat..
http://www.geocities.com/wildcat_sport/alex_davidson.html


Can anyone suggest:
- Plans
- Builder
- Opinion

My boat
http://www.geocities.com/wildcat_sport/

Thanks
Jean-S Berard

-- jasipati --

 

throwaway your omc my way

Hi, I have a 1980 22' cruiser with a 230 OMC that needs the entire, complete sterndrive (somebody stole the darn thing), so if you decide to get rid of your OMC, pls let me know and we can talk.

Alternatively, I am thinking of possibly converting to jet drive. Does anyone have any thoughts on that?

Kevin

 

I have a similar line of question, which I am posting to a new thread: "Classic Bertram 25, replace I/Os or convert to O/B?". I would sincerely appreciate feedback, opinions, etc.