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Re: 26M w/ 90 HP
Posted: Wed Dec 01, 2010 3:13 pm
by DaveB
Victor, you have the 2001 Mac.X and I the 1997 model.
I have tried to get the width of the DF90A but without results. Max. width I can have is 16 inches as the boarding ladder will hit engine if raised. What is the width of the 90? I now have the Honda BF50 and that has 14.7 width and ladder clears by 1.25 inches and boarding 14 inches between rudder up and engine.
Dave
vkmaynard wrote:Octaman wrote:I can't help asking (no offence to you Victor) as it has become clear over time that the behaviour of the
is different to the
(or vice versa if you like
)
I really could not comprehend the differnce until the day my wife shot this video
http://www.youtube.com/watch?v=eovBozRo5gg
The M is definitely more of a displacement hull. You will notice how it plows thru the water vs. the X. One of our forum mates has a new DF90A on his M in Russia and is only seeing around 24 MPH with the same 4 blade prop. Don't know how much weight he has onboard. Not sure what the incremental improvement is between the 70, 90, 115, 140 on an M. The X shows a significant improvement with more power (90 is enough for us).
One thing I'll throw out for a 90+ Hp consideration; keep in mind high speed cruising (like our trips to Ocracoke and in the Chesapeake 45+mi). If you have a smaller motor it will operate at or near WOT (like the Honda 50) and eat a lot of gas and struggle to get you there. The newer Suzuki DF90A uses less gas in that case because it is not struggling (4200 RPM 18 MPH w/o ballast mast up boat loaded). If you get the X on a "real" plane (boat rides over the bow wave around 21+ MPH) then there is no challenge on fuel economy compared to a boat that is plowing thru the water. On a 45 mi trip (head wind, used motor) Billy (140Hp X) used about the same amount of gas at 24 MPH as we did at 13 MPH WOT on the Honda 50.
Victor
Re: 26M w/ 90 HP
Posted: Wed Dec 01, 2010 3:52 pm
by ROAD Soldier
Dave If you have the capabilities to mount a 90HP and manufacture and mount the backing plate you need to securely hold the engine, you have the capabilities to move a freaking ladder. If you think you don't after you buy a 90HP Suzuki feel free to play Santa Clause and give it to me. I have no issues with moving a ladder if need be.
Re: 26M w/ 90 HP
Posted: Wed Dec 01, 2010 5:06 pm
by vkmaynard
The ladder misses with the new DF90A smaller cowling. You still need to pay attention to straighten the motor a reasonable amount before lifting. It is the same cowling size as the DF70/DF80.
Erik purchased a 2002 DF90 and the ladder hits his motor(he just moved it).
Dave I'll get you the measurements tomorrow. Our boat is in a storage lot 5 min from our house.
Ron you sound like the Drill Sergent psychiatrist on the GEICO add
I fully expect Ron to end up with a 90 soon. After all, he joined the X AC club
Victor
Re: 26M w/ 90 HP
Posted: Wed Dec 01, 2010 5:38 pm
by ROAD Soldier
vkmaynard wrote:The ladder misses with the new DF90A smaller cowling. You still need to pay attention to straighten the motor a reasonable amount before lifting. It is the same cowling size as the DF70/DF80.
Erik purchased a 2002 DF90 and the ladder hits his motor(he just moved it).
Dave I'll get you the measurements tomorrow. Our boat is in a storage lot 5 min from our house.
Ron you sound like the Drill Sergent psychiatrist on the GEICO add
I fully expect Ron to end up with a 90 soon. After all, he joined the X AC club
Victor
Shut-up crybaby and go back to mamby bamby land.
Re: 26M w/ 90 HP
Posted: Wed Dec 01, 2010 11:42 pm
by Octaman
Dave,
Go to this link,
https://secure.suzuki.com/marine/brochures/?model=DF90
on the Suzuki Marine website and download the brochure of the DF 90/80/70
On the last page you have all the dimensions you need, including the swing angles.
Moving the ladder is no big deal and will not compromise the boat in any way. Go for the bigger motor
if that's what you want.
Octaman
Re: 26M w/ 90 HP
Posted: Thu Dec 02, 2010 12:15 am
by tom clayton
I have the df 70 at wot rpm 4500 no ballast gps 22.5 mph should my motor revs be higher do i need a different prop?
Re: 26M w/ 90 HP
Posted: Thu Dec 02, 2010 1:49 am
by Octaman
tom clayton wrote:I have the df 70 at wot rpm 4500 no ballast gps 22.5 mph should my motor revs be higher do i need a different prop?
Tom,
I am assuming your DF70 is the 1.300cc model prior to 2008.
If so, your DF70 is most certainly overloaded; 4.500 rpm at WOT is way too low ! - you need a lower pitch. What are the dimensions of your prop you are using? I suspect it could be a 15' pitch ???
Suzuki indicates max revs between 5.200 and 5.800 for this outboard. This is what you need to target.
22.5 mph is about 19.5 knots - That's fast! I got 19.8 knots with my 70 and the stock prop (do not recall the dimensions at this moment) when the boat was new and completely empty, six years ago. Never saw that figure on my GPS again.
Expect to loose some speed when you decrease the pitch but you will save your engine.
If you have been enjoying the 19+ knot speed, then, my friend, you, like myself, need to power up
Join the club.
Octaman
Re: 26M w/ 90 HP
Posted: Thu Dec 02, 2010 2:17 am
by tom clayton
sorry if this post twice, i have a 2009 motor with a stock prop direct from the BWY. I was thinking i might need to reprop i was thinking about a 4 blade any advantage in doing that? your right i do want to go faster when im not sailing but new warrantees make that a challenge thanks Tom.
Re: 26M w/ 90 HP
Posted: Thu Dec 02, 2010 4:46 am
by Octaman
2009 would probably make that the new DF70A (1.500cc).
I'm sorry I have no experience with this motor.
It is important to establish which of the two motors is in question as there is quite a difference between the two.
In any case, you need to re-prop.
Re: 26M w/ 90 HP
Posted: Thu Dec 02, 2010 7:11 am
by vkmaynard
tom clayton wrote:I have the df 70 at wot rpm 4500 no ballast gps 22.5 mph should my motor revs be higher do i need a different prop?
I would try the Solas 3413-138-15 (13.75 x 15 Amita 4) and have 1"-2" pitch removed after initial testing, "empty". KEEP THE DIAMETER (see thread comments on my tests). I have the same prop with 1" of pitch removed but am turning around 6200 WOT (6300 MAX spec) no ballast and "empty". That is the smallest pitch 4 blade Solas makes with that diameter.
Test the boat without ballast and the way you normally use it "empty" to get near WOT spec. In our case we will run with the mast down, sometimes off, with no cushions, no head, no water, two batteries, AC, 18 gal gas for wakeboarding. That was our no ballast empty condition for propping the motor as close to WOT spec as possible. Then when you have a full load the motor will be real close to max horse power RPMs.
Victor
Re: 26M w/ 90 HP
Posted: Thu Dec 02, 2010 7:46 am
by Octaman
Victor
Removing pitch ???
I don't see how this can be done.
What I know for sure the prop shops CAN do is reduce the load on a prop by cutting off a strip of the trailing edge of the blades. This reduces the surface of the blades. The pitch stays the same.
This results in achieving higher revs - although the approch is very different to switching to a prop with a lower pitch.
Is this what you mean by 'removing pitch'?
Octaman
Re: 26M w/ 90 HP
Posted: Thu Dec 02, 2010 8:32 am
by vkmaynard
The prop is hammered on "pitch blocks" which are like a mandrel (
http://www.rundquist.com/bpbm.htm). Then it is measure and tweaked for consistency. The shop can also adjust the cup on the blade tip. You would NEVER want trim the edge and remove the anti-cavitation cup.
The shop we used in VA only charge $30 and did a great job. They added RPMs and speed for all conditions and most likely improved the fuel economy at higher cruise speeds.
Victor
Re: 26M w/ 90 HP
Posted: Thu Dec 02, 2010 11:48 am
by Octaman
Very interesting Victor
I was not aware that this was possible and, regretfully, I very much doubt if this is a service available in my area.
I totally agree with your comment 'never wanting to trim the edge' not only because it may take the cup away but also because you are actually spoiling the shape of the foil. It is like reefing in a foresail (partially) and expecting the remaining sail to perform like the whole thing does.
But this is what I was told they do here. I'm going to have to research this again more thoroughly.
Your comment is an eye-opener for me; thanks.
Octaman
Re: 26M w/ 90 HP
Posted: Thu Dec 02, 2010 12:01 pm
by tom clayton
The blade i have is a 13,875x15 3 blade, thanks for everyones input will start to look for a shop here on Ohau that works on props my motor is the DF70A, thanks
Re: 26M w/ 90 HP
Posted: Thu Dec 02, 2010 12:04 pm
by vkmaynard
The "pitch blocks" are specific to the brand and type of propeller.
Victor