Prop Question

Night_Sailor

Night_Sailor

Member
I bought a Fisher 20 CC last year. This year I bit the bullet and followed the advice of many and bought a new ETEC. I chose the 150HP small block. I would have liked to go bigger but it seemed adequate for my needs and I also got a 7 year warranty on it.

My boat has a cut down transom and instead of putting on a 20" shaft outboard, I decided to use a jack plate and a 25" shaft. There won't be much adjust-ability because I'll be using 5" of the 5.5" vertical lift. This should also allow me to tilt the motor back as it is supposed to tilt. I bought the boat without a splash board, which I assume was tossed out because the existing motor interfered with it when tilted back.

My transom is solid, however, I'm worried the jack plate will add a lot of torque to the top of the transom. I plan to bolt a 3/8" thick aluminum plate across the transom for extra mechanical strength, and to minimize water intrusion.

So, the final decision I have to make is what size prop? Should I go stainless or aluminum? I have heard that I might get an extra 1 mph out of stainless. I'm open to suggestions and recommendations.

Also, what spares should I keep? Drain plug? Spare nut? Spare prop?
 
If you bought the engine new, then your dealer will set it up for you. That is a requirement per EVINRUDE is that all engines are setup by the dealer BEFORE they are registered and a warranty issued. EVINRUDE lost quite a few etecs early on because of improper setup(mostly propping), so they now require the engine to be setup by an authorized dealer. If you bought the engine used, then you need to be pretty critical with your propping of it. What kind of prop depends alot on the hull type and your useage of it.
 
ALSO the jack plate will add absolutely NO more force or stress to the transom.... The force comes from the prop and the mathematical lever arm is exactly from the prop to the top mounting holes in the transom and the fulcrum is the lowest contact point of the transom

You could have a 20" motor or a 120" motor w a 100" jack plate and the leverage would be the same

Now a 25" motor on a 25" transom on the other hand WOULD apply more leverage to the transom than your setup. ..
You are worried about a nonexistent issue.... Forget the reenforcement plate..... Instead just look at blocking water... MUCH less strength needed for that.... Plastic would be my choice
 
FERM and smoke do have valid points.

I normally carry one of the spare props I have tested previously, not to mention the stuff to install/replace it with, all the way down to the thrust washer.
The prop composition usually depends on your habits, I happen to like the stainless.

Other spares also depends on your habits. I usually keep a spare portable bilge pump with alligator clips and hose connected, spare drain plugs, fuses, oil, anchor/rope, one more safety vest and throwable than needed. If offshore fishing or camping or riding the grandkids around there will be other things added to the pile of stuff.

Depending on what your jack plate setback is and how you normally load the boat, you might need to raise the engine yet higher than a regular transom mount. A 5" setback might need to go up 1 or 2 bolt holes, a 10" might need to go up 2 or 4 bolt holes.

If you don't have a prop already, I'd expect to start out with about a 15x17" stainless and go from there. If the engine is setup correctly and depending on your habits you might need to go to a 15" or 19" and/or anything in between. This is where a dealer setup situation will save you time/money and get the best performance.
 
Before I would make a remondation, I would need to know what you're boating is. If you run shallow or an area with alot of obstructions, I'd go aluminum(props are cheaper and easier to fix than lower units). If you are after max performance then stainless is your prop. And how you are going to use it will dictate which style and brand I'd reccomend. Theres dozens of styles of props out now, each for a different useage. Its not the olden days where your choices were just stainless or aluminum.
 
THEFERMANATOR said:
Before I would make a remondation, I would need to know what you're boating is. If you run shallow or an area with alot of obstructions, I'd go aluminum(props are cheaper and easier to fix than lower units). If you are after max performance then stainless is your prop. And how you are going to use it will dictate which style and brand I'd reccomend. Theres dozens of styles of props out now, each for a different useage. Its not the olden days where your choices were just stainless or aluminum.
Click to expand...

I run aluminum props for this exact reason
 
I will be running it mostly in Long Island Sound (deep water zero visibility). I may pull it to the Florida Keys (very shallow/good daytime visibility), and occasionally up to the Georgian Bay and French River in Ontario (rocky bottoms, clear water/good daytime visibility). I bought this boat originally because I wanted a trailerable boat.
 
Is it worth hundreds of dollars to you to top out at 42.5 instead of 41.2?

Is most of your running WOT, just on plane, trolling, or looking for best economy.

What's most important to you? Hole shot, cruising, top end, etc
 
Are you wanting to cruise with it, or run her WOT alot? If you after a good affordable propeller for cruising, then the SOLAS 4 blade aluminum would be high up on my list. If you want a good top end, then a SOLAS stainless 3 blade would be a good choice. I reccomend SOLAS because they are cheap, and so far all of them I have run have been VERY smooth running. They are also the OEM prop for HONDA to give you a clue as to there quality.
 
That's real interesting, I know you guys know your stuff, but I never use anything BUT stainless mostly because I'm in shallow water. I have worried about tearing up gears but it's never happened. Running the islands here you are bound to go through sand or mud. Composite prop - the blades break off. AL props bend, cup & wear away, Stainless prop - it just got a sharpening.

Part of the reason for my decision is after working on those islands I learned about the disastrous results of losing power in shallow surf. I have a couple of friends who rolled a whaler, what a story!

Oyster beds & more solid objects do more harm, but I still run the Michigan 19 pitch that was on it when I bought it, just a bit sharper & lighter after all these years.
 
Hijack...

So I'm turning 5700 at wot with a 3 blade 17p with a light load. Not sure diameter, but it's on a Yamaha 225 4 stroke. This is my Robalo, not the V. I'd like more holeshot and could care less about top end but do want to consider efficiency. I really liked the 4 blade on my V. If I switch to 4 blade, what pitch should I be considering?
 
For an engine like the YAMAHA, I would be looking at a mIRAGE or MIRAGE copy. They are 3 blade large diamter props that bite in HARD, give good holeshot, EXCELLENT cruise, and hold the water like nobodys business. You will sacrifice a bit on the top end, but the MIRAGE style large diamter props are just great all round performers offshore on bigger boats.
 
THEFERMANATOR said:
For an engine like the YAMAHA, I would be looking at a mIRAGE or MIRAGE copy. They are 3 blade large diamter props that bite in HARD, give good holeshot, EXCELLENT cruise, and hold the water like nobodys business. You will sacrifice a bit on the top end, but the MIRAGE style large diamter props are just great all round performers offshore on bigger boats.
Click to expand...

what he said, its hard to beat. The new mercury enertia series is supposed to be the ticket for four strokes, I haven't played with them or seen them on anyones boat yet. The Mirage is always my go to on everyday use boats, if nothing else,it gives me a good starting point to go with when reproping as they are very consistent on their performance. I just went thru reproping a 25 Intrepid(twin 150 Opti's) for one of my customers, we started with 21 Tempest and it wouldn't tune any rpm(5000). I told him he needed somewhere between a 17 and 19 Mirage as my first guess. I changed the motor height and four different sets of props he brought me(17 mirage, 19 mirage, 19 revo, 17 protech). Ended up with 19P Mirage cut down a little to get the rpms up. The revo had the best midrange but lost 5 mph at top end and wouldn't turn over 4800, the protech worked real good, but the 17p number was a lie as it wouldn't turn as much as the 19 Revo. The prop guy he was buying the props from said the 15 protech sucked and he didn't stock them. WE were also trying to get the boat to stop porpoising. I had raised the engine height to try and get the rpms up. The boat had been rigged at Fon Du Lac by Mercury ( former WIsconsin Fish and Game boat). Intrepid swore the Tempest was the way to go(it sucked). The mirages cut his fuel burn at cruise by 6 gph, He lost 1 mph over the tempest at WOT but picked up 2 MPH at cruise. Hard to beat a Mirage
 
Spares - I couldn't agree more. I love the mirage and mirage plus props.

My experience has been that the older mirage props will turn about 200 RPM's faster than the mirage plus. I recently bought a 17p Enertia (14.75") and it's faster than both the 17p mirage and 17 mirage plus. I suspect that the 15.5" diameter of the mirage plus / mirage might be the difference in speed. The mirage on my boat clearly has a better low speed performance vs enertia. It'll hold 10/11/12/13 mph without any trouble, but Enertia is 2mph faster WOT.
 
I saw the video on CSC Big Shrimpin, nice work and way to step out there and take a chance on that prop. I want to try one on the flats boat. It has the new 115 4S Merc with the giant lower unit like the v-6 motors. I took the Thunderbolt (Mirage Copy) off the Wellcraft and got nearly 10 mpg at 12 mph on plane at 2500 RPM. High five holds better with the motor jacked up but mileage is not as good at only 7.7 mpg at the same speed. Mirage was the most efficient of the five props I tested. Again and again the Mirage seems to win of the props I tested anyways (Tempest, Quicksilver, Thunderbolt (Mirage Copy), High Five, and another prop that Ferman loaned me.
Not as great of a selection in aluminum props. No fancy derivatives like the Tempest, Enertia, Chopper, Cleaver in aluminum. Not that any of those would work in all applications, just stating the obvious.
 
It's done

I left the country for the last two weeks, delivering a yacht to St Thomas. So I didn't discuss the project much with the installers. I was not totally sure what size motor to get. I knew I wanted a white small block and decided to go for the 200HP model.

The original plan was to use a jack plate. I requsted the installer put on an aluminum splash plate to raise my transom back up to the original 25". This morphed into putting on two thick aluminum plates and eliminating the jack plate. They put spacers in between them also, which stiffens up an already strong transom.

For the prop, I let the installer decide for me. They picked a three blade stainless steel--ok I guess fast is good. I wanted the digital gauges--two of the large ones. I may add two small gauges to fill the gaps.

Next up, is registering the boat and I'll probably rewire the whole boat.

I am thinking about removing the T-Top and repainting it and that might be a perfect time to form up a hardtop.

I am a happy camper. The motor looks so good, I'll have to spruce up the boat. I'm thinking about using a hard finish bottom paint, and perhaps at some point I'll repaint the topsides.

IMG_2928_zps0spvxbb0.jpg
 
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