Volvo Prop to Solas

[jmb23802]

Looking for guidance from anyone that has moved from a Volvo Penta (Aluminum) prop to a Solas Amita 4 (Aluminum) prop. Want to hit the nail on the head first try if I can after an experience in my previous boat buying several props (and losing $$) before I got it all dialed in.

My current setup and results: 2003 5.7 GXi (4600-5000 RPM WOT range) with a VP 14.25 x 21 3-blade aluminum prop. With full 54 gal tank of gas, gear and my crew I estimate a weight of about 800 lbs (capacity plate says 1,500 lbs max) I am reaching 4600 RPM trimmed out at WOT.

I would like to run as close to 5000 RPM as possible with my 800# crew and a full tank of gas at WOT for optimal performance, longevity, and so we can bring along a 2-3 adult friends and maybe a couple more kids, coolers, etc. and stay inside the recommended RPM range so we can get on plane for towing, etc. without lugging the engine down too much.

Current logic (mine) is that going from 21p to 19p will move me from 4600 RPM up to 5000 RPM (assuming 1"p = 200 RPM). Adding a 4th blade would bring it back down to 4800-4900 RPM (assuming 4th blade = 100-200 RPM decrease). However, I fear the switch from a VP prop to a Solas Amita 4 throws my logic out the window due to the different design cues in the two brands.

What I do know is that I need to go down in pitch. Basically, I think I am trying to decide between a 14.25 x 19 Amita 4 OR a 14.5 x 17 Amita 4. Afraid the 17 will be too low (would like to stay as close to 5000 RPM as possible), but the 19 might only get me to 4800 (depends on design differences). Looking for advice from anyone with experience switch from AL Volvo prop to Amita 4 prop.

 

[jimmbo]

You don't say what hull you have...
You are going to lose more than 400 rpm with an extra blade. Myself, I would stick with 3 blades and drop down to a 17 or 18 when you are loaded up with extra Guests. Even with lower pitches, the extra weight will affect acceleration, and the size of the wake, which might or might not be desirable depending on what you are towing.

 

[TunaFish389]

When I switched from a three blade 19p to a four blade 17p same diameter, same brand/model I gained 300 rpms. This was with a 3.0 mercuiser so take it for what its worth.

 

[jmb23802]

You don't say what hull you have...
You are going to lose more than 400 rpm with an extra blade. Myself, I would stick with 3 blades and drop down to a 17 or 18 when you are loaded up with extra Guests. Even with lower pitches, the extra weight will affect acceleration, and the size of the wake, which might or might not be desirable depending on what you are towing.

The hull is a Regal 2200 bowrider with the "Fastrac" hull step.

I would like to go with a 4 blade to get more stern lift and help the boat get on plane faster, hold plane at slower tube towing speeds, better handling around the dock, etc.

 

[jimmbo]

A boat's hull shape. Load, and location of Load are what will determine what its Minimum Planing Speed is. If you want the Boat to assume a planing Attitude at lower speeds, Trim Tabs are your best Option. 3 Blade Props like the Enertia, are very good, both with Holeshot and Top End.

 

[H20Rat]

A boat's hull shape. Load, and location of Load are what will determine what its Minimum Planing Speed is.

Props contribute to stern lift, some much more than others. With no other changes, I've had a prop change drop the planing speed by 3-4 mph. The action is the same as trim tabs, if you lift the stern, the bow comes down.

My previous deck boat had a standard merc (no idea what model) 3 blade on it. Went to a high lift 4 blade, and my planing speed went from barely stable at 21 mph to rock solid minimum speed at 17 mph.

 

[jmb23802]

Update...

I spoke with a prop shop that sells the Solas aluminum props. Here's what they told me:

A 4-blade Solas aluminum prop one step down in pitch from the 3-blade aluminum Volvo Penta I have now (so, 19 instead of 21) will yield roughly the same RPM as my current VP prop. So, in effort to get the RPMs closer to 5000 at WOT with the Solas 4-blade I have to go down in pitch another step to a 17.

Based upon the shop's recommendations I ordered the 14.5 x 17 4-blade Solas. I likely won't be able to test this prop for a month or so when I get back to the lake but will try to reply back here with the results, good or bad.

 

[Hoserpoppasmurf]

We had the Glastron MX175 with 130 Volvo. Went to Enertia 20 pitch and played with vent hole size. It made all the difference to the boat. With vent holes at about 3/8" it allowed enough slippage at take off to prevent the little engine from over loading, yet we still had 43mph (gps). We pulled 4 man tubes, or two slalom skiers with good pull-not competion good but certainly enough for those hanging on to the end of the rope.

 

[QBhoy]

I’d stick with a good brand...and a 3 blade too. 19” enertia, I’d say to you.

 

[TunaFish389]

Don't worry about what people say about Solas.. Its a well known respectable brand. You might get a couple of mph from others at twice the price.

 

[QBhoy]

Don't worry about what people say about Solas.. Its a well known respectable brand. You might get a couple of mph from others at twice the price.

Kind of agree, but there is no doubt they are a the bottom of the scale in prop terms. Finish and tolerance are nowhere near as good or accurate as a quality merc prop. To me, a good well suited quality prop is the single biggest improvement to a boat, you can make.
Time and time again I’ve seen a standard black max merc ally prop out perform a stainless solas prop in every way, at the same pitch and 3 blades. Big believer in getting the best out a boat with a good prop. It’s like putting a real crappy set of tyres on a performance car really. Sure, they’ll work...but you won’t be getting the best out it. Just my thoughts.

On a side note and to not put too much of a downer on the solas...for some reason...they make excellent impeller/props for jet skis. Just not so much for an outboard or outdrive. Go figure ??

 

[jimmbo]

Mercury makes many Excellent Props, and even their lowest price line more often than not, will beat the Competition.

When it comes to my fave, the Enertia, there is no Competition, though the RAKER is an Excellent 2nd choice

 

[QBhoy]

Mercury makes many Excellent Props, and even their lowest price line more often than not, will beat the Competition.

When it comes to my fave, the Enertia, there is no Competition, though the RAKER is an Excellent 2nd choice

Agree jimmbo. Should have listened to you a long time ago about the enertia. Amazing things. Also expensive though. Can never discount the also incredible laser 2 for all round ability though.
I currently have the laser back on to sell the enertia. The enertia is that good I want another but with a 1” different pitch.

 

[jimmbo]

The Enertia is not cheap, but I consider it Good Value for the Money

 

[porscheguy]

Good luck selling the enertia. I’ve tried several times to unload my excess props which are all in mint condition, and people are rarely interested. Since there aren’t many to begin with, is there a better market for used props on your side of the pond?

 

[jimmbo]

I've had several people try to buy mine at the Lake

 

[jmb23802]

Well, not sure how buying an Enertia prop at 6X the price (3X wouldn't change my opinion) and a hub kit to convert a Merc prop for a VP outdrive on top of that, or adding trim tabs, or buying a boat with a different hull so I can get on plane faster addresses my question about expectations when moving to a different brand ALUMINUM prop. All of the problems I am experiencing with the way I use the boat can be solved without buying an expensive SS prop like the Enertia (I've done it before with another boat); but, thanks anyway - always more fun to spend someone else's money, I guess.

That said, if I hate the Amita 4 prop I may reconsider. A few years ago I tested more than one Volvo prop, a Viper prop and a Solas prop (all on a different boat that I now do not have) and the Solas beat them all hands down. So I am giving Solas first crack at it this time. If I hate the Amita 4, I may reconsider stainless steel and possibly even the Enertia. We'll see.

 

[jimmbo]

In 1999, I tried a Viper on one of my outboards. It too Underwhelmed me. I then tried a RAKER, and liked it. When I got the VP I/O I had the RAKER rehubbed with a VP hub. It worked very well. 4 yrs later I borrowed an Enertia from the Dealer, and after a thorough comparison, ordered one for myself. That was 14 yrs ago, so my cost of ownership is less than $41/yr for the Enertia(including Hub Kit), and $32/yr for the RAKER, that includes the rehubbing and later repairing the RAKER in 2002 when it had an argument with a rock pile.

 

[Gary GAS]

I,am using the solas amita 4 and the merc spitfire 4 blade on my 19ft blue water open bow boat with the volvo 4.3 motor and find them both to be the best props i have used. I did have the enertia prop on my 21 ft searay and did not see any improvement with it over the vengence prop that came with the boat. I found it to be way over priced and the amita 4 to be a great value.

 

[jmb23802]

Finally got out to the lake and here's the results of my tests:

The Solas Amita 4 with 17" pitch provided great hole shot and acceleration but RPM's were excessive (IMO) at cruise speeds and when I went WOT the tach swept all the way up to 5400 RPM and was still creeping up before the engine stuttered due to either the fuel cut off or the engine outran the fuel feed (max recommended WOT is 5000 on this engine). Also, on my boat, the four blade prop made the boat more sensitive overall to weight distribution while on plane. We had to be more careful about seating arrangements to get the boat evened out than we had experienced with the three blade props - I presume this was because the stern was planing higher in the water and getting more tippy due to the deep rise hull.

Next I tried a three blade Viper SS prop in 21" pitch that I had used on my old boat temporarily and I was familiar with. To my surprise, the Viper did not produce an egregious amount of bow rise like it had done on my smaller and lighter boat and the WOT RPM trimmed out with a typical load fell in around 4750-4800, right in the middle of the recommended RPM range. The boat topped out somewhere around 50 mph +/- which is right around where it should be at that RPM.

Based upon the tests above, I believe I either did not get a good test on the AL three blade that came with my boat or perhaps that prop has been "massaged" to a higher pitch than stamped on the hub. For now, I am happy with the Viper prop performance and will continue to run this prop on the boat. In the future I will likely look to replace it with something that gives me a little less bow rise and a max RPM when loaded out right around 5000-5100 RPM but I have other fish to fry first at this point. When I do replace this prop, I may stick with a three blade simply due to the weight distribution sensitivity I experienced with the four blade.

I have not decided whether to keep the AL Amita 4 or sell it. I may hang onto it for water sports and spare prop duty.