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View Full Version : One of these things is not like the other



zelatore
06-03-2009, 01:12 PM
My new prop from Griz arrived today, as did another prop set. Which one do you think I should use?





(the 'other' props are a matched pair for an IPS drive)

mikev
06-03-2009, 01:48 PM
The one with four blades cause more is always better in America. Just kidding I dont have a clue what one would work best on your boat. if it was me i would grab the GPS and spend a day at the lake trying them all out.

SilverBack
06-03-2009, 01:58 PM
I think that you may have a clearance problem with the two big props!!:wink:

HOWARD O
06-03-2009, 02:07 PM
My new prop from Griz arrived today, as did another prop set. Which one do you think I should use?
(the 'other' props are a matched pair for an IPS drive)

I didn't realize the IPS uses a 3 and 4 blade prop. I remember my duoprop and buying SS props for it. I bet THOSE for an IPS drive are a pretty penny! Neat technology, what's been your experience with them? Work well?

The Hedgehog
06-03-2009, 02:57 PM
The 4 blade looks like it will not provide enough bow lift:outtahere:

MOP
06-03-2009, 03:18 PM
Lets see the 3 blade looks like a likely candidate!

BUIZILLA
06-03-2009, 08:06 PM
why does Volvo clip the blades like that ?

Just Say N20
06-03-2009, 10:54 PM
I didn't realize the IPS uses a 3 and 4 blade prop. I remember my duoprop and buying SS props for it. I bet THOSE for an IPS drive are a pretty penny! Neat technology, what's been your experience with them? Work well?

They are phenomenal! When I was working at Tiara, they built the first boat actually design from the "ground up" for the Volvo IPS. Most companies initially retrofit an existing design, which didn't allow them to benefit from all the plusses.

They allow you to do things with a boat that you shouldn't be able to do, when using their joy stick control. The drives are independently articulating, as well as capable of opposite thrust (one forward, the other reverse).

They are also very efficient compared to a traditional inboard. It feels like you are on a very big runabout they way they turn when you are really up and running.

http://i26.photobucket.com/albums/c111/streb2005/IPS500_twin_highres.jpg

zelatore
06-03-2009, 11:03 PM
Well, I was going to try the IPS props on my Bravo but I had to take them out to the boss's dock so they could be installed on our 50 Marquis. Something about him running it at night up the river....best I don't ask too many questions.

It is a bit odd that they run a 3 blade/4 blade combo. Also odd the way the clip the ends of the blades. I can't tell you any of the logic behind it, only that that's the way they build 'em.

Before dropping them off for installation on the boat, I took them by my local propscan guy to have him digitize them and store the specs since Volvo doesn't like to publish actual numbers for IPS or Duo-prop props sets and instead just labels them 'H6' or something like that. One prop was dead-nuts on spec, while the other had one blade slightly out. Not much, but a little. Better than the average new prop. And now we have a digital template to repair the the stuff that got banged up.

And yeah, they're pricey. Volvo's never been scared to charge for parts - retail on the set is around $2500. And this boat's got 3 sets, so don't go doing anything stupid!

(you know, like running 30 knots after dark up a river full of debris :bonk:)

zelatore
06-03-2009, 11:16 PM
They are phenomenal! When I was working at Tiara, they built the first boat actually design from the "ground up" for the Volvo IPS. Most companies initially retrofit an existing design, which didn't allow them to benefit from all the plusses.

They allow you to do things with a boat that you shouldn't be able to do, when using their joy stick control. The drives are independently articulating, as well as capable of opposite thrust (one forward, the other reverse).

They are also very efficient compared to a traditional inboard. It feels like you are on a very big runabout they way they turn when you are really up and running.



I hate to say it, but I think I'm the only guy on the planet who doesn't actually like them. :eek:

Yeah, the joystick is neat, but I can do anything it can using a bow thruster and regular twin inboards. And in fact, I'm far more graceful around the dock with regular twins. I never seem to get exactly what I expect from the joystick. Try to go diagonal with it and it really gets confused!

I liken it to 'digital' vs 'analog'. With regular twins, I can drift up to a dock at say 30*, click the opposite side engine into reverse to check my headway and settle the stern agianst the dock, and do it all with no drama. Very 'analog'. With the IPS joystick, You drive at right-angles. Pull up along-side the dock. Stop. Move boat sideways. Stop. No grace to it at all. I've also found the control logic to be pretty course. Seems like you're always jerking the boat from place to place instead of getting small inputs. I understand (but haven't actually driven one to verify) that the Merc/Cummins Zeus drive is better with fine control, although I believe the IPS is superior in most every other way.

But, it does make it simple for new boaters, that's for sure! And it's a hell of a sales tool - people love the joystick! And they are very sporty to drive, giving great helm response. We actually have to digitally dial down the response for our flybridge boats to keep people from getting crazy at the helm. I'm still waiting for Volvo to do a GPS based station-keeping option like the Zeus has - I think they call it 'skyhook' or something. I've been in plenty of situations where it would have been great to just hit a button and have the boat stay in one place while I went out to tend to lines or fenders or an anchor or what have you.

All that said, if I was in the market for a boat that was available with IPS or regular straight shafts, I'd probably do the the IPS. For one thing, the economy is much better. Volvo was claiming some huge number like 25-30% early on - I haven't seen that kind of increase but it's definitely better. Plus if you design the boat for it you can get a nice increase in usable interior space. And of course with more and more of these type systems coming out (ZF is launching there own version as well) they are clearly the wave of the future and I suspect NOT having them will hurt resale somewhere down the road.

Just Say N20
06-04-2009, 08:29 AM
I can see your point on the graceful thing.

On the first demo I went on, I volunteered to be the first "test subject." He had me position the stern of the boat (40') towards a buoy, and then said he wanted me to make the boat go around the buoy once, keeping the stern pointed at the buoy the whole time. Picture the boat being a spoke on a wheel, with the bow always pointing away from the buoy. I was able to do it the first time, not because I'm good (I don't know that you can be good at a skill the first time you do it), but because the system seemed very intuitive.

About halfway around the circle, he said, "Now keep going, but move the boat 10' closer to the buoy as you continue around." I was able to do this too. I don't believe I could duplicate this maneuver in a conventional inboard boat. I don't know if "real life" you would ever need to do this, but it certainly demonstrated the capabilities of the drive system.

In the first IPS designed boat, they were able to add another stateroom/head with the space saved by the IPS drive system. And, it was a 40' boat with twin IPS 600s (420 actual hp each if I remember correctly) that went about 38 mph. I have never seen a conventional 40' boat with only 840 hp run almost 40 mph.

Another thing we saw was wives really liking the fact that if something happened to hubby, they felt like they could actually bring the boat back and get it into the slip.

zelatore
06-04-2009, 10:16 AM
OK, the spokes on a wheel thing is a pretty good trick. I might try that sometime on a demo.

As mentioned, I can take it or leave it when it comes to the joystick but it's hard to argue with the efficiency and performance. Our 40 with the same power also sees similar results. And our 50 with triple IPS 600s gives over 40 mph at 66 gph. That's pretty impressive!

Here's a sheet of some early testing I did with the boat; I was experimenting with running on one or two motors at low speeds for economy as well as high speeds with all three.

First column is # of engines. Second is RPM. 3rd is speed in knots, 4th speed in MPH. 5th is gallons per hour, and last is miles per gallon. I don't know any way to get that kind of performance out of straight shafs.

Sorry for the jumbled up chart, I can't make the formating work on in the message so it's a little hard to read.

Eng RPM KTS MPH GPH MPG
1 1000 4.9 5.6 1.2 4.70
1 1200 5.9 6.8 1.9 3.57

2 idle 3.9 4.5 1.2 3.74
2 800 5.3 6.1 1.8 3.39
2 1200 7.2 8.3 3.8 2.18

3 idle 4.4 5.1 1.5 3.38
3 800 6 6.9 2.3 3.00
3 1200 8.1 9.3 5.3 1.76
3 3000 29.6 34.1 42 0.81
3 3300 34.1 39.2 52 0.75
3 3560 37.5 43.2 66 0.65