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#463459 - 06/16/09 04:45 PM Need Recomendation on Prop for Glastron GX 185  
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Stevo Offline
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Stevo  Offline
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Billings, Montana
I just bought a 2004 Glastron GX 185. It has a Volvo Penta 4.3 L engine in it. I want to be able to really pull skiers and wake boarders out of the hole and want some decent cruising speeds 45 MPH or so. It has a 14 1/4 x 21 on it and it does ok but, can i do better? This is my first boat so I am clueless on this stuff. I run on flathead lake Montana that is about 2900 ft above sea level.

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#463460 - 06/16/09 04:48 PM Re: Need Recomendation on Prop for Glastron GX 185 [Re: Stevo]  
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WaterMutt Offline
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Massachusetts
I'd try a 14.5x19, or 18 if SS.


Malibu Wakesetter 23XTI
Bryant 214 Limited (gone, but not forgotten)

"That's my boat..."
-Forest Gump

#463461 - 06/16/09 04:51 PM Re: Need Recomendation on Prop for Glastron GX 185 [Re: WaterMutt]  
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D-Rod Offline
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What are you RPMs when the throttle is mashed and the drive trimmed up/out?


-YOLO
#463466 - 06/16/09 05:13 PM Re: Need Recomendation on Prop for Glastron GX 185 [Re: D-Rod]  
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captkevin Online content
Admiral
captkevin  Online Content
Admiral

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Chicago, IL
4 blade stainless - check out hillmarine.com


2004 Rinker 232
2010 Dodge Ram Crew Cab Laramie 4x4
#463467 - 06/16/09 05:13 PM Re: Need Recomendation on Prop for Glastron GX 185 [Re: captkevin]  
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captkevin Online content
Admiral
captkevin  Online Content
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Chicago, IL
i'd try the 19 pitch


2004 Rinker 232
2010 Dodge Ram Crew Cab Laramie 4x4
#463471 - 06/16/09 07:03 PM Re: Need Recomendation on Prop for Glastron GX 185 [Re: captkevin]  
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Stevo Offline
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Stevo  Offline
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Billings, Montana
Thanks guys. I think my RPM is about 4000 What is the performance differance between a four blade and a three blade. Whats the diff?

#463472 - 06/16/09 07:14 PM Re: Need Recomendation on Prop for Glastron GX 185 [Re: captkevin]  
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prober Offline
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Eastern Washington
I've heard great things about Hill marine props and horrible things about thier customer service.

First, before you change anything you need to know what you have now. By that I mean that you need to know what RPM and speed you are running when at wide open throttle,(WOT). Your engine manual will give a range for this that you need to keep within, for your engine I think it is 4400-4800 RPM. The idea is to have the engine at the high side of the range when running very light, say 2 people and half tank of gas. You also want to trim the drive up a little until the bow starts to porpoise or get light and then give a small trim down just until the porpoiseing goes away. You will notice that this will raise the RPM a little since it raises most of the boat above the water.

In your case with the prop you have now I am guessing you will be at about 4200-4400 RPM which is OK but when you get more people on board and try to pull someone as well it will be lugging the motor. This is very hard on a boat motor, sort of like leaving a stop light in your car in third gear.

Anyway, once you have all the numbers you can figure out which prop to buy. There is no "magic" prop. Generally if you go down in pitch from a 21 to a 19 the hole shot and pulling power will be better but the top speed will be a little slower. Go up from a 21 to a 23 and the reverse will be true. It is for this reason that many people have two props, one for sports and one for cruiseing.

Now here is where it gets tricky. figureing out which pitch you want is the easy part. The problem is that there are so many other things that a prop affects besides hole shot and top speed. Things like bow lift, stern lift, blowout, cavitation, handleing in turns, vibration, ability to turn in reverse are all greatly affected by the prop. And it gets harder because one prop will work great on your buddies boat and be terrible on yours.I bought a prop once that worked great on my freinds boat and it would blow out in corners on mine and I had a poirposeing problem that could not be trimmed out. That prop is still decorating my garage wall today.

So with all that in mind, I suggest you use a prop shop if you have one in your area. They usually will allow you to try several props before you buy so that you can see if it has any undesireable affects. Might cost you a little more than on-line but at least you won't have an expensive garage ornament.

Also, Volvo has a great 4 blade aluminum prop that will get your hole shot improvement without sacrificeing too much top speed. I think it's about $150.00

#463484 - 06/16/09 08:47 PM Re: Need Recomendation on Prop for Glastron GX 185 [Re: prober]  
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Frantically Relaxing Offline
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While you're not at a REAL high altitude, I wouldn't rule out a 17" pitch prop, especially in stainless. I don't think you'll lose that much top end either, but you might have to watch your revs...


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#463593 - 06/17/09 10:39 PM Re: Need Recomendation on Prop for Glastron GX 185 [Re: Frantically Relaxing]  
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RX 4 Fun Offline
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IL
I guess it depends on your gear ratio, but we used to have a 17' Four Winns with the VP 4.3/SX drive and it swung a 14 1/4x23 alum prop with ease and it had a strong hole shot. 4600rpm max (which if I remember correctly the rpm range on it was 4200-4600). It would run around 50mph. You are at a higher elevation but so I don't know how much that would effect things.

Hard to really tell what your situation is w/o an accurate wot mph and rpm reading. Need to use a GPS to verify speedo accuracy.


'14 Ram 1500 Laramie Crew
'18 Chaparral 267 SSX
#464087 - 06/24/09 09:32 AM Re: Need Recomendation on Prop for Glastron GX 185 [Re: RX 4 Fun]  
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williemon Offline
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Columbus Georgia
I used to run a 14x17" 3 blade SS on my 17' with 3.0L merc. Speed wise I could only get 35 to 36 mph at 4600 rpm (max rating). I could over rev easy though, but did not worry about that. Made a point to make sure myself and all who drove never ran over 4000 rpm. I propped this way just to get the holeshot since 95% of the time we were pulling somebody.

I now use a 19 pitch High Five with the PVS plug system. I get the same holeshot, perhaps just a bit quicker as with the 17 pitch 3 blade. I get the same speeds per rps as with the 3 blade. I do get better holding power for the wakeboarders.

For the slalom skiers, the PVS helps. I took out 2 plugs. On holeshot with a slalom skier, engine rpms jump to 4000 to 4300 rpm. This helps in getting into the highest power band that the 3.0 can create and will minimize drag times since the engine/prop will be making more torque and can get the boat/skier moving faster. With the 3 blade, it would get to about 2500 and just stall out there untill the skier plained out enough to allow the engine/prop to pickup revs. This caused an increase in skier drag time over the high five.

With the 4.3L, you will have more torque than my 3.0L. I would look to have the rpms running over, at, or very close to max to get the most ommph out of the holeshot with a typical load, say 3/4 tank of gas and 4 persons on board. This may make top speed suffer though, which is why I recommend a prop with the PVS vent system and 4 blades at least. That way, you can prop it to get close to, or at max rpm and have the speed you want, and then be able to taylor the rpms to hit a certain rpm during holeshot with a skier in the water. Slalom skiers will demand the most oomph at holeshot. 2 ski skiers, wakeboarders, kneeboarders, tubers will need less holeshot. With my 3.0L, weight of towed person and experiance made a huge difference except in slalom. With slalom, even guys that knew how to slalom would drag forever if over 160 lbs with the 3 blade. The 5 blade with pvs did help that quite a bit.

You might even look into smart tabs. That is a different train of thought. I myself also use a fin bolted to my outdrive. I love the way I can take off while sitting in the chair and never lose the horizion.

BTW, I will sell my 3 blade 14x17 SS prop if you or anybody would like it.

#464095 - 06/24/09 10:41 AM Re: Need Recomendation on Prop for Glastron GX 185 [Re: williemon]  
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Stevo Offline
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Stevo  Offline
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Billings, Montana
Ok boys. I put a 19 pitch on this weakend and I was fully loaded with my family of 6 and full fuel. Ithe boat came to plane quickly and at wide open throttle I was going 42mph at 4800 rpm. The engine says i should run max 4600. So i think i am over reving it when i am in cruise mode. Pulling a 120 lb wake boarder we did fine out of the hole as well. I think i will try a 21 athis weakend.

#464128 - 06/24/09 03:20 PM Re: Need Recomendation on Prop for Glastron GX 185 [Re: Stevo]  
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prober Offline
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Eastern Washington
I think your right where you should be unless top speed is more important. I wouldn't worry about going over your RPM range by 200 RPM since you most likely won't be there very long.

Throw the other prop back on there if you are planning on a long cruise.

#464135 - 06/24/09 05:13 PM Re: Need Recomendation on Prop for Glastron GX 185 [Re: prober]  
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bsbladine Offline
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I have a 2003 larson 190 with the volvo 4.3 and I run a 19 pitch 4-blade ss. The boat will run about 52 mph with 4 adults in it and will pull a 170lb wakeboarder with no problem. The rpm's run right about 4300 when topped out. I used to run a mercury high five with a 23 pitch, way to much money for the performance. I would look to propmd.com if you need any suggestions they are great.

#464200 - 06/25/09 11:10 AM Re: Need Recomendation on Prop for Glastron GX 185 [Re: bsbladine]  
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J&J Offline
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J&J  Offline
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Wisconsin
Stevo,

We have a 2004 Glastron GX185 with the Volvo 4.3 GXi engine. Not sure if you have the fuel injection like we do, but I would think we should be pretty close. Also, we live in Wisconsin so I am not sure how elevation is different compared to you, but I can tell you I am running a 4 blade Michigan wheel 14x20 Vortex aluminum propeller. We have been very happy with its performance. Hole shot is great, pulls skier up with no problem (I am a larger guy 220 lbs and have no problem getting up on 2 skies, I have also skied double with my wife and the boat has had no problem getting both of us up) holds plane at much lower speed (great for the little nieces and nephews), does not wander as much at low speeds, and can still get 52 mph at full speed (need to verify with GPS but for now I can dream!) At full throttle, with myself, wife, normal safety gear with skiing gear, and 1/4 tank of gas, we get 4900 rpm and 52 mph. With full tank of gas, and 4 more adults the rmps drop to 4750 and top speed of 50. (Have only done this once. Not enough room for everyone to be in the cockpit and I will never go full speed ahead with passengers in the bow!) We had 3 blade 14.25x23 aluminum and it was a dog out of the hole. The 14.25x21 3 blade aluminum improved holeshot quite abit and put us in the upper rpm range of the engine. Heard great things about the benefits of a 4 blade, so we tried the current prop mentioned above. For the price and added benifts it is hard to beat.

Sorry for being long winded, but thought I would share what I have considering our boats are similar. If you have any questions, please let me know.

Also, I am bit surprised by the large gain of 800 rpms from going down 2" in pitch. While not impossible, I would have expected 400 to 500 rpms max. I think the 19 is probably right where you need to be. Are you sure the max rpm is only 4600? According to our engine 4800 is max (maybe because ours is fuel injected)?


smile 2005 Glastron GX205 - 5.0GXi
2014 Ram 1500 Crew Cab
#464202 - 06/25/09 11:16 AM Re: Need Recomendation on Prop for Glastron GX 185 [Re: bsbladine]  
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williemon Offline
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williemon  Offline
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Columbus Georgia
Are those 4 or 3 blades? SS or Alum? You started with a 21 pitch. Whats different about the 21 you will try ? I would not worry if you can run a couple hundred over the max rpm. I would not run it there , but the extra torque you get from being able to over rev a little is great for holeshot. Just pull back on the throttle if you start to go over 4600 while cruising.

#464204 - 06/25/09 11:40 AM Re: Need Recomendation on Prop for Glastron GX 185 [Re: williemon]  
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Stevo Offline
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Stevo  Offline
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Billings, Montana
Great info. I would think that you would loose some rpm when you go from a three blade to a four blade. is this true? I do cavitate really bad in tight corners. it sounds line the 4 blade may help this issue?

#464207 - 06/25/09 12:02 PM Re: Need Recomendation on Prop for Glastron GX 185 [Re: Stevo]  
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J&J Offline
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J&J  Offline
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Wisconsin
It all depends on the type, aluminum or stainless, and the manufacturer. In our case we stayed aluminum. Michigan wheel recommended that if we use a 21" 3 blade, we should use a 20" 4 blade to keep approximately the same rpm. For us, this was exactly the case. Hill Marine propers recommends same for same meaning a 21" 3 blade aluminum could be replaced with a 21" stainless 4 blade of theirs for they are already compensated for the extra blade. As you can tell there are many factors that go into selecting the correct prop. Trial an error is the only way you will find the correct prop for your boat and your use! With that being said, I think you should try a 20" 4 blade aluminum (assuming your orginal prop was aluminum) By going to the 20" it should bring your rpms down a bit (since you seem concened about it), should help with cavitation, and should maintain decent hole shot. However if it were me, as it has been said by others, I would not worry about the 200 rpm over at full throttle, and would be tempted to try an 18" 4 blade aluminum for improved handling and hole shot. Good Luck and please let us know what you decide!


smile 2005 Glastron GX205 - 5.0GXi
2014 Ram 1500 Crew Cab
#464267 - 06/25/09 07:17 PM Re: Need Recomendation on Prop for Glastron GX 185 [Re: williemon]  
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Stevo Offline
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Stevo  Offline
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Billings, Montana
I can not seam to find a 14 1/4 four blade 20 pitch prop to buy..stainless

#464380 - 06/26/09 11:56 AM Re: Need Recomendation on Prop for Glastron GX 185 [Re: Stevo]  
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J&J Offline
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J&J  Offline
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Wisconsin
I don't think I have been able to find one either. However there are many varables that go into prop selection. Prop diameter being one of them. I think as long as you can stay at or slightly under the diameter, you should be alright. Michigan Wheel has the Apollo that is 14.125x20. Might be worth shot. Or maybe Hill Marine 14.25x19 or 14.25x 21 4 blade.

Again, I went from a 14.25x21 standard Volvo Penta aluminum 3 blade to a 14x20 4 blade aluminum Michigan Wheel prop, and have been very happy. I don't know how the smaller diameter works into the equation, maybe someone here can explain. In the end, all I know is the rpms stayed the same, and the perfomance is much improved.


smile 2005 Glastron GX205 - 5.0GXi
2014 Ram 1500 Crew Cab
#464511 - 06/27/09 09:14 PM Re: Need Recomendation on Prop for Glastron GX 185 [Re: J&J]  
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williemon Offline
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Columbus Georgia
Smaller diameter gets you less blade area. That way, when you add the 4th blade and keep diameter the same, there is more blade area and drag. This could cause the prop to not spin up fast enough in the water, or could scrub top speed. By makeing the diameter smaller, you cut those issues out by a certain percent while still having more than a 3 blade.


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