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Author Topic:   correct propellers
whaler222 posted 03-08-2002 07:45 PM ET (US)   Profile for whaler222   Send Email to whaler222  
can anyone tell me what size props i need? i have a 22 outrage whaler drive and am putting twin 125 non counter rotating mercs on the back. i need to know size and pitch i need. thanx
peteinsf posted 03-08-2002 09:07 PM ET (US)     Profile for peteinsf    
Try Merc's prop selector!

Hyperlink to Prop Selector.

Pete

fireball posted 03-08-2002 09:25 PM ET (US)     Profile for fireball  Send Email to fireball     
I hate to break this news, but before props you will need load levelers on the boat to counter those mercs...f
whaler222 posted 03-08-2002 11:20 PM ET (US)     Profile for whaler222  Send Email to whaler222     
what are load levelers? how much are they? thanx
Steve Leone posted 03-09-2002 11:06 AM ET (US)     Profile for Steve Leone  Send Email to Steve Leone     
i think he means trim tabs, steve out.
Alan Hiccock posted 03-11-2002 03:17 PM ET (US)     Profile for Alan Hiccock  Send Email to Alan Hiccock     
Whats the deal with Merc? How do they come up with these #'s?
I went to the prop selector link provided by Peteinsf
Ive got a 15 BW Sport w/a 70 Yammie, I thought I'd see what would be the right prop for me from the " selector"
I put in 950 lbs. F.Glass fishing boat with a 75 because they dont have 70's
The outcome was 69.75 mph's ?????
& to speak to a merc per for the right prop,
70 MPH'S ????????
They think people are stupid or something.
even with a 75hp the boat would have a hard time breaking 55mph's.
Comon Merc.!
peteinsf posted 03-11-2002 03:43 PM ET (US)     Profile for peteinsf    
Alan,

In my experience the selector is pretty good if you estimate the boat weight correctly.

To do this you need the weight of the passangers the fuel, motor weight any oil, and other goodies you bring on board...

I would guess your total weight would be more then 950.

Also I have never cross checked their application on a boat smaller then a Outrage 18'.

Good Luck, let me know what you figure out,

Pete

Alan Hiccock posted 03-11-2002 03:59 PM ET (US)     Profile for Alan Hiccock  Send Email to Alan Hiccock     
Ohh motor weight is included? Yeah.. ya sure?
I'll try with that included and see what she says.
OK, just came back from the " selector "
Alan I punched in 1200 lbs. total with a 75 2 stroke 15' er. It told me 60+ mph's top speed????

HuH , no way ..

peteinsf posted 03-11-2002 04:15 PM ET (US)     Profile for peteinsf    
Alan,

Try different boat types for fun...

Pete

lhg posted 03-11-2002 05:45 PM ET (US)     Profile for lhg    
I, too, have found the Merc prop selector to show speed a bit on the high side. My printed Merc prop charts show that a Merc 75 on a 15 should run between 44-52 mph at up to 1400lb total load.

This prop selector is really only for current Mercury engines and their respective gearing, so prop pitch indication may now be correct at all for another brand, or earlier Mercury, engine.

A Mercury 75 shouldn't be compared to a Yamaha 70. The Yamaha is no match in top end. That's like comparing 80 HP with 65 HP.

A better Mercury equivalent for the Yamaha 70 would be the Merc 60. They are both putting out about 65 HP.

lhg posted 03-11-2002 06:02 PM ET (US)     Profile for lhg    
Getting back to the twin 125's on a 22 WD, the prop chart shows 20" Laser II props and speeds of 43-49 MPH. Total load range between 3000 - 4800 lbs.

Be sure to get them up at least 3 bolt holes on the WD. You won't need stern lifters (trim tabs) with a Whaler Drive. Can't be installed anyway!

Regarding your hydraulic steering, for best results use a side mount cylinder between engines, installed in a reversed tilt tube in the port engine. this will counter prop torque. See Bracket article in reference section.

Alan Hiccock posted 03-11-2002 07:20 PM ET (US)     Profile for Alan Hiccock  Send Email to Alan Hiccock     
I punched in " bassboat" 15' with a 60 2 stroke, 1100 lbs.. selector said 54.9 mph's.
thats loco.
IHG, I know the mercs really wind up but ya really think my new Yamaha 70 inj. with 40 hrs. is putting out 65 hp?
I REALLY doubt it. I'm going to get the speed on GPS when I change the " winterized fogged plugs" but from having a bunch of boats I can pretty much bet that this boat now is doing 45+ with me {185 lbs. & 12 gals gas} on my 15 sport with bottom paint.
I bet it's putting out all 70 ponies & then some. I read somewhere that Yamaha doesnt underrate or keep them governed anymore as I think they once did.
lhg posted 03-11-2002 07:52 PM ET (US)     Profile for lhg    
Alan, I really don't have prop rating figures for these engines, but here are engine sizes:(all 3 cylinder, loop charged)

Merc 60 2-stroke: 58 cubes
Yamaha 70: 52 cubes
Merc 75 2-stroke: 85 cubes

You tell me. As you can see, the Merc 60 is a bigger engine. Mercury is not noted for low HP per cubic inch displacement! And they are also known for under-rating HP. Years ago (in the 50's), nobody could figure out how the little Merc 20's would walk away from the OMC 25's. It was actually putting out over 30 HP! They're still using this idea. I'll bet the two engines (Merc 60 and Yam 70) will run neck and neck on most boats.

Alan Hiccock posted 03-11-2002 09:35 PM ET (US)     Profile for Alan Hiccock  Send Email to Alan Hiccock     
IHG, I dont understand the logic? The fact that the Merc 60 has more cubes then the Yammie 70 means it puts out more HP or even more HP per cubic " ?
My Harley Davidson Electraglide had a 1200 cc's engine, put out maybe 60 HP.
A Yamaha V Max has 1100 cc's & makes 145 HP.
I mean I could go on for years thinking of smaller engines that produce more ponies then larger ones.
It's all in the engineering.
I read here on this site that Yammie's were slightly slower on the 15 sport then same hp Mercs and I beleive it, those Mercs really wind up, but i DOUBT Yamaha would have thier 70's making 65hp. I can tell you from the feel of mine , it's not. I also read somewhere else in a couple places that they { yammie }also exceed the HP ratings by a little all though not as much as Merc. I'd bet almost anything the same boat, same weight that a Yammie 70 would beat a merc 60 though. I dont think Merc overpowers by that much nor Yammie is overly conservative with thier HP ratings that it would win, be close maybe but the Yammie would win. Heck this 70 inj. with the sys. chk. digital tach & hour meter costs $ 6500 installed surely it would be able to take out a 60 merc! He he he
At least I hope so..One thing I know for sure , she'll last longer. you get what you pay for. take care,
Alan
peteinsf posted 03-11-2002 09:48 PM ET (US)     Profile for peteinsf    
Larry,

Do you think that is true for all Mercury motor sizes or only select model ranges?

As an example do you think an 1989 Merc 2400cc 200HP would out perform a 1989 OMC 3000cc 200HP (letís leave the older two-thirsty-five out of the discussion). If so is there and other advantage to a bigger displacement motor?

I do know in the 60-90HP range it is harder to compare motors. In that range there are 2-3 and 4 cyl motors with wide displacement differences.

Pete

peteinsf posted 03-11-2002 10:04 PM ET (US)     Profile for peteinsf    
That was supposed to be:

"If so, is there another advantage..."

lhg posted 03-11-2002 11:14 PM ET (US)     Profile for lhg    
You guys are asking me questions I can't really answer. Clark Roberts knows a lot more comparative information on engine HP's and relative performance than I do.

I would agree that cubes aren't everything, but of all brands, cubes in Mercs are a pretty good sign of relative HP. I say this because for years they were always smaller displacement, but higher performing engines.
That why they basically own the go-fast, racing and bassboat markets. So now, if one has more cubes than say an OMC or Yamaha, it's likely it is more powerful. But maybe not always. Who knows, since as you say, design engineering and manufacturing tolerances do make a difference. Just ask Bombardier that question.

I had '89 200's on my Whaler, and yes I am convinced they were faster than either the Yamaha or OMC 200's of that day, even though the cubes were less. The 60 degree V design made a big difference, and they were lighter also, as much as 75 lbs lighter than the OMC's. When I bought my 115 Mercs, I also thought they were faster than the OMC V-4 115 offering, even though displacement of 100 cubes was the same. The well balanced in-line 6 small bore design made the difference. Today, I am also convinced a 3.0 liter Merc 225 EFI will outrun the same size 3.1 liter Yamaha. A mechanic told me the engine's really putting out about 245HP, or more. After all, they get 300HP out of this in a high performance version.

I actually like the Yamaha 70, and think its a nice, clean running engine, compact and light. I'm sure it's plenty of HP for a 15 classic. I have heard the Merc 75 is too much for the boat, and too heavy, for most to be comfortable with. How a Merc 60 runs on the boat I have no idea.

I think the NMMA says an engine HP can be within 10% of prop rating, either way. The new Merc/Yamaha 4 strokes are a good example of this. On the same engine, Yamaha goes over the true HP of about 95 (with a 100HP rating so they can charge more!) and Mercury goes under the true HP at 90. For the same engine, the Merc 90 4-stroke generally sells for about $1000 less. So we can all spend our money the way we want to. Marketing, after all, is important in getting us to part with our funds.

I should say that I have been a 32 year owner of Mercury Outboards, but am not in the boating business at all, and have no financial interest in promoting them. I feel they are a good product, and I have gotten several thousand hours out every one I have owned. Their strongest suit, since 1984, is how well they hold up to salt corrosion and UV paint degradation. And you do get a lot attention on the water with "black in back".
If nothing else, the brand is clearly recognized for speed.

True story: I'm out cruising at about 25 mph around Gills Rock, at the tip of the WI Door County peninsula, in my 18 Outrage with the twin 115 Mercs. Behind me, I see a USCG 22 Guardian rapidly approaching, with four guys on board. They motion to us to stop, and they come up alongside us. My first question, is "what'd I do?". "Oh, nothing, we just wanted to see your Whaler and check out those engines". I thought I was in trouble for the HP. "Want to trade them for our workhorse Johnson 100's? These things are just not fast enough on this boat, and we sure would love to have those Merc 115's instead." They were clearly more interested in the engines than the Whaler. Usually, it's the opposite. Those were the days when OMC had a lock on the government contract for outboards, and Whalers could not be rigged with Mercurys.

jimh posted 03-12-2002 01:06 AM ET (US)     Profile for jimh  Send Email to jimh     
[Fixed that long URI]
Alan Hiccock posted 03-12-2002 08:30 AM ET (US)     Profile for Alan Hiccock  Send Email to Alan Hiccock     
I read that the manufacturers have to have thier engines HP rating within 10% of claimed HP.
So in theroy the 60 HP Merc might take out my 70 Yammie, what do I know?!
I found info. on this subject elseware after posting.
One interesting thing is I think 1974 was when the HP was to be measured @ the prop by law & that was when you saw engines like the 88 OMC's which were 100's the reay before and the 110's ect.
Alan
whaler222 posted 03-13-2002 11:55 PM ET (US)     Profile for whaler222  Send Email to whaler222     
lhg,

are your merc 115's counter rotating? if not does it tend to ride to one side? thanx for any info.

Blackeagle posted 03-14-2002 12:54 AM ET (US)     Profile for Blackeagle  Send Email to Blackeagle     
whaler222
Check this thread out:
http://continuouswave.com/ubb/Forum1/HTML/001652.html

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