The Limits of Mercruiser 260 Power

[rlb2252]

I?m most interested in buying a mid ?80?s Sea Ray cruiser. The boats from this era tended to come with the Mercruiser 260/Alpha 1 combo, apparently quite a successful pairing.

The range of vessel lengths and weights powered by this setup is somewhat surprising going from 21 foot Cuddy?s to the 268 Sun Dancer.

The 268 Sun Dancer is a lot of boat, in both length and weight. This is especially the case when maxed out with its full 100 gallon fuel load, ten passengers legal limit, and large fresh water tank (I believe this can hold nearly a 100 gallons as well.)

Can the same engine that powers these smaller cruisers do adequate justice to a boat literally thousands of pounds heavier? Will it still plane easily? Cruise at rated speed?

 

[rbh]

Re: The Limits of Mercruiser 260 Power

There were also 27-28 foot /8.6-10.6 on beam as well with the single 260hp
you could also get them with twin 260hp as well as other engine combos.
Srv, weekender, amberjack, sedan bridge and sundancer to name a couple.
rob

 

[captmello]

Re: The Limits of Mercruiser 260 Power

My boat has the same engine with a volvo outdrive. It is also on the small side for that engine.

I doubt the 25-27 footers would plane, maybe with trim tabs. Sea Rays of that generation were heavy to begin with.

I wouldn't hesitate to buy a boat with the 5.7 again. Maybe you should test drive a couple. Let us know what you find.

 

[rlb2252]

Re: The Limits of Mercruiser 260 Power

My boat has the same engine with a volvo outdrive. It is also on the small side for that engine.

I doubt the 25-27 footers would plane, maybe with trim tabs. Sea Rays of that generation were heavy to begin with.

I wouldn't hesitate to buy a boat with the 5.7 again. Maybe you should test drive a couple. Let us know what you find.

I've driven 22 and 23 foot Sea Rays with that engine. Both only carried me and the owner.

Both handled well at that lighter weight.

 

[arks]

Re: The Limits of Mercruiser 260 Power

Can the same engine that powers these smaller cruisers do adequate justice to a boat literally thousands of pounds heavier?

Yes but, as with everything, there's a catch. The heavier the boat, the slower it will acheive plane. Acceleration and speed with be compromised.

Will it still plane easily?

Well, if the engine is performing properly and the boat trimmed properly then yes it will plane. Easily? Well, that answer is subjective. Let's just say that a big block in the same boat would be noticably quicker and faster.

Cruise at rated speed?

Don't know what 'rated speed' means.....manufacturers don't speed rate their hulls.

 

[45Auto]

Re: The Limits of Mercruiser 260 Power

I've driven a 2006 Sea Ray 260 Sundancer with a 300HP 5.7L and a B3 outdrive. It is a slug to say the least. Very slow to get up on plane, cruises in the mid-20's at just over 4000 RPM, and tops out in the low 30's. I can't imagine a carbed 5.7 in an older 268 being any better. You'll be pushing right around 30 pounds per HP. I don't like to work my motors that hard. Definitely test drive one, you may find you're more interested in another configuration.

My 30' Sundancer has twin 260's, and is much more responsive. Dry weight on it is 9500, so each HP has to push about 20 pounds. That seems to me to be a comfortable power/weight ratio for a cruiser.

 

[26aftcab454]

Re: The Limits of Mercruiser 260 Power

My 1984 26 ft Wellcraft aft cabin -came with a 260hp motor new- it now has a 1996 7.4 Bravo3.

I bought the boat last year so can't comment on the preformance then but now runs 43MPH WOT 4600RPM on GPS on a good day just me. I usually don't run over 4000 RPM .
It planes easy enough and mostly cruise at 3400RPM at 28MPH- with the tabs down I can run about 23mph at 2800RPM

this is a very heavy boat - 3/4" plywood hull sandwiched between 1/4" fiberglass inside & out, genset-hot water heater-big freshwater holding tank-95 gal fuel -yada yada yada...it must have been a turd with 260hp.

 

[jtybt]

Re: The Limits of Mercruiser 260 Power

...and besides the limiting factor of the size of the engine, The alpha drive has a maximum prop diameter of 16". If you're going larger than 24' consider the BIII counter-rotating props or the BII with the larger diameter props.

Overall, the counter-rotating drives, both Volvo and merc, will get the most out of whatever engine they mate up to.

 

[Grand Larsony]

Re: The Limits of Mercruiser 260 Power

Friend has 1987 SR 268 Sundancer with single 350\260 Merc. Yes, it is a bit slow to get on plane but not terrible. He usually manages his weight pretty carefully (half-tanks of gas & water max, moves coolers, etc. forward) and it's fine.

Really, you'll need to get on the boat and see how you like it. My buddy is happy with his setup.

 

[thundercraft260]

Re: The Limits of Mercruiser 260 Power

Just my two cents...I have a 92 thundercraft 260 express with 5.7L bravo 2 carbed engine. Not exactly the same boat you are looking at but it will give you an idea. The boat weighs 5700 lbs dry....and i have all the gadgets hot water, fresh water blah blah blah. Went on vacation with 2 adults & 4 teenagers went o.k.

Planing is not a problem, a little time but managing the weight and it's didtribution goes a long way. Cruising speed is around 25 mph at 3600 rpm, top speed 37 mph at 4200 rpm, rarely go there...

I didn't want a boat any bigger as they all have twins....I didn't want the hassle of twins so I settled for this set up. It does me fine

Good luck

John

 

[n2ostroker]

Re: The Limits of Mercruiser 260 Power

One of our boats is an 87 Bayliner 2450 Ciera with the 260 5.7. It runs good with it. Probably upper 30's on top end. With 5-6 adults(2-3 of those fairly large adults), coolers, gas, etc it gets on plane, a little slow but it's not bad. With only 1-2 people it runs great fro the size it is.