Inflatable Diving Boat - which motor Should I go with - 2 stroke vs. 4 stroke?

[LoriP]

My husband and I live in Northern California and frequently dive the Pacific from Monterey north. We purchased a 10' Rib inflatable dive boat but are not sure what type of motor to go with, so I thought I'd get some feedback from fellow Scuba divers.

We're going to be hand launching this boat mostly (for Ab diving), so a 2 stoke is lighter (by 40-50 pounds), but you can't purchase a new 2 stroke in California.

Now a 4 stroke is very nice with no oil mixing, starts with one or two pulls, and is environmentally friendly and can be used anywhere in California (even Lake Tahoe), but it's so heavy, and will make hand launching difficult.

Some friends of ours have a 4 stroke, but him and his wife manage the hand launching. For re-sale though, which would be the best option? Cost is not an issue for us. I know the 4-strokes cost more.

I'd like some opinions. Thanks.

:D

[Scubaroo]

LoriP once bubbled...
environmentally friendlyThere's your answer :)

[boomx5]

But, what about Rule #1?;)

[zboss]

4 Stroke motors are FAR superior to 2 strokes in every way... of course you pay out the ying-yang for that. One thing to keep in mind that a four stroke will provide a longer life and therefor a higher resale value. You also need a slightly smaller horsepower 4 stroke to get the job done, so a 50 4-stroke is about equivelent to a 65 HP 2-stroke.

Besides - they are just plain quiet.

[JT2]

zboss once bubbled... You also need a slightly smaller horsepower 4 stroke to get the job done, so a 50 4-stroke is about equivelent to a 65 HP 2-stroke. I agree with just about everything here accept for the above statement. The 4-stroke is going to have a broader though lower rpm torque curve, which will allow it to pull a higher pitched prop in the lower rpm range thus giving it more bottom end and this also makes it better suited for heavy loads. Simply saying that you need less horsepower with a 4-stroke is not exactly true for every application, although I think in LoriP's situation the 4-stroke would be the best choice if they can lug it around. I am not a fan of 2-stroke eegbeaters, but pound for pound they can't be beat.

[Adam Samansky]

'nuf said.

Adam

[LoriP]

Thanks everyone - Looks like 4 stroke is the way to go!

[Bob3]

There is legislation on the table out here in CA to make 4-strokers mandatory statewide as well, so a 2-stroker may be obsolete if a year or three.

[herman]

LoriP once bubbled...
We purchased a 10' Rib inflatable dive boat but are not sure what type of motor to go with,

so a 2 stoke is lighter (by 40-50 pounds),

:D

Just cutious, how big of a OB are you putting on a 10ft boat? My 50 hp 2 stroke with TT does not weigh much more than 225 lbs and my 1968 6 hp is in the 40lb range. Must be a big one to save 40-50 lbs.

[colonelchuck]

Let's face it, when you look at the ocean, it is hard not to care about the stuff that lives in it. The amount of oil that a single two stroke puts in the water is not much, but it does add up. We all have to suck it up and do the right thing if we want the planet to last.

Chuck Donaldson
Emergency Response Manager
Oregon Dept of Environmental Quality:maniac: :maniac:

[zboss]

JT2 once bubbled...
I agree with just about everything here accept for the above statement. The 4-stroke is going to have a broader though lower rpm torque curve, which will allow it to pull a higher pitched prop in the lower rpm range thus giving it more bottom end and this also makes it better suited for heavy loads. Simply saying that you need less horsepower with a 4-stroke is not exactly true for every application, although I think in LoriP's situation the 4-stroke would be the best choice if they can lug it around. I am not a fan of 2-stroke eegbeaters, but pound for pound they can't be beat.

Absolutely I agree - different engines are good for different applications. In general I have found that for beating across open water my Yamaha 90 HP 2 stroke wasn't nearly as good as my Honda 75 HP 4-stroke.

[LoriP]

In reply to Heman (I'm not sure how you all put those "quotes" on these threads).

Anyway, our 10' inflatable will only hold a 15 hp max. On low HP 4 stroke outboards, the different in weight between a 2 stroke and 4 stroke is large. A 15 hp 4 stroke motor weights about 115 lbs. , whereas a 2 stroke is about 70 lbs. The lightest 4stroke I've found is a Yamaha at 99 lbs. 9.9 hp 4-strokes are only about 5 lbs. lighter than the 15.

We're definately going with a 4-stroke now.

[sailnj]

2 - Strokes are still considered to be much less problematic in the repair department than 4-strokes. Also, the weight is a big factor. If you plan to use the boat and motor outside the continental US you can forget about ever getting parts to repair your 4-stroke. 2- strokes are much cheaper and there is also a much larger used parts market (which is also important if something major goes since many times replacement new parts can cost almost as much as a new motor) All that said if you go with the tree huggers suggestion then I would highly recommend a Yahama - they build very reliable and durable uncomplicated engines. This month's Practical Sailor magazine reviewed small four strokes if you want an un-biased opinion (they have no advertising)

[etype]

'outside the continental us' you won't be able to find parts?

Sure..., honda, yamaha, mariner only sell 4-stroke parts to americans...
I think anyone who feels any responsiblity for the enviroment would agree that unless absolutely necessary a 4stroke is the way to go. I have a 25 hp Honda on my Zodiac (in canada no less)...i;ve had meriads of different outboards in every horsepower range...and i have to tell you...4 strokes are sweet in every regard. 2strokes are not ony enviromentally messy, but they make a hell of a lot more noise and mixing oil/gas for fuel is not a fun thing to do compared to just gas .
Go with 4 stroke, you will be thankful you did.

[kavka]

4 stroke Yamaha (high trust) weights the same as old 25 2 stroke, but wouldn't trade any more. 4 stroke runs without any problems 2 stroke !?...

[DennisS]

How much lifting/carrying of the engine are you going to be doing. I have a 25 hp 2 stroke on my 12 foot, curse it every time I move it and wish I'd bought a 15 hp. What's your back worth.

[zeN||]

Your engine size is related to the rating on your boat, which should be stated on the plate on the transom. I just got this 9.9 hp 2 stroke for my achilles and you can bet it's going in the water! ~Z

[nwdiver2]

4 stroke as you know the 2 strokes a present can not be purchased in some places and in the next few years will be illegal in many places.

[100days-a-year]

2 strokes are not going to be illegal in 2 many places as the newer DI 2 strokes burn very clean.4strokes are heavier ,slower, no NOT have any fuel consumtion advantage and have more moving parts to fail and need adjustment.DI technology has revolutionized 2 stroke motors and every year the engines avaiable with it are getting smaller.Try some boating/sailing websites on comparisons,also the motor manufacturers have actual tests of thier motors on various boats on thier websites.