I'm looking for more top end speed and think I have hit the performance barrier as far as Solas aluminium propellers are considered. Hill Marine has a nice selection of stainless steel propellers so I decided to get one for my Selva Madeira 40 XS from Ebay. Unfortunately they do not advertise propellers for 2T Selva outboards so I decided to buy a propeller labeled as "Signature-Semi-Cleaver-13-Spline-Race-Propeller-18P-for-Yamaha-F18R3L-117". After all I have been using Yamaha G-series propellers without problems so this should fit like a glove!
Hill Marine Semi Cleaver 11 1/4 X 18
This propeller came with a Michigan Wheels XHS hub kit 117 for Yamaha.
I tried to install this hub kit and quite quickly noticed that although Selva Madeira 40 XS is compatible with Yamaha G-series propellers it DOES NOT mean that one can replace the stock thrust washer with Yamaha thrust washer that comes with XHS hub kit 117!
Both have 13 splines which is fine, the problem is that Selva thrust washer has narrowing teeth whereas Yamaha thrust washer's teeth do not narrow. Hopefully the images below give some explanation.
Selva Madeira 40 XS stock thrust washer
Michigan Wheels XHS 117 thrust washer (part number 991243)
It was possible to install the propeller but due to differences in the shape of teeth the propeller was a little "shaky" and I'm not comfortable to use it like this. I'm not sure how to proceed, I might alter the XHS thrust washer or find some way to use stock thrust washer with this Hill Marine propeller.
I'll post an update once I have figured out what to do. If you have some information please use the commenting functionality below! :)
Installing XHS thrust washer 991243.
Thrust washer does not go all the way.
The semi cleaver looks good but does not fit 100 %!
It has been a long and dark winter but now spring is arriving slowly but surely.
I want to install a very different kind of propeller so I need to remove the stock thrust washer.
Unfortunately it's so stuck that I failed to remove it when the boat was still is in the water.
Today I tried to remove it again by hand but no luck. I sprayed lots of CRC Penetrating Oil and let it do its job for 15 minutes, then I applied it even more and waited some time.
After that I used a large flat head screwdriver and carefully tried to move it. It's very easy to damage the paint on lower unit. I tried from different positions and finally it moved.
It could be that this was the first time the thrust washer was removed since the outboard came from the factory!
Today my Selva Madeira was not starting although the battery was fully charged, basically nothing happened when I turned the key, the only thing I heard was a small whining noise coming from the motor.
I checked that the safety leash was connected, the gear was in neutral position and the motor start cables were properly attached to the battery.
First I thought that there is some kind of electrical failure so I opened the engine cover,
I tried to rotate the flywheel and noticed that it was stuck. It was quite hard to notice but the starter motor drive gear was barely touching the flywheel gear but enough to block the rotation.
I tried to rotate the flywheel using an emergency pull rope but it was too stuck.
Then I sprayed a little WD-40 on the top of the starter motor and gave two knocks with a wrench,
the starter motor drive gear dropped a little and the the flywheel turned and was freed.
After that the motor started without any problems :)
Tap here gently if your flywheel seems to be stuck.
How much does one inch propeller pitch change affect motor revolutions per minute ?
If you do some googling some say that increasing propeller pitch by one inch decreases motor rpm 200-400, some say that increasing propeller pitch by two inches has 300-400 rpm effect. Boat U.S. states that the effect is 200 rpm if the propeller is cupped and the diameter stays the same. Stuart Allen from Dangar Marine also seems to acknowledge this 200 rpm per inch rule.
I wanted to test this in practice, of course every boat and motor combination is unique and the results will vary. I'm talking about Solas Amita 3 11x16 versus Solas Amita 3 11x17. Some say that Solas Amita 3 is a cupped propeller and in this case the only difference should be the pitch size as the diameter is the same (11").
So here are the results:
With Solas Amita 3 11x16 my Selva Madeira 40 XS reached about 5 650 rpm with wide-open throttle. That is above the recommended maximum 5 500 rpm. The motor was trimmed as up as possible.
With Solas Amita 3 11x17 the motor reached about 5 300 rpm. The top speed was two knots lower with this propeller.
Solas Amita 3 labels.
So one inch increase in the propeller pitch resulted to 350 rpm decrease.
I was a little surprised of this result, I was expecting a drop of 200-250 rpm.
It's quite annoying that with higher pitch propeller you don't reach the recommended rpm range and with lower pitch you go over the limit.
This is just speculation but could it be that aluminium is not a good enough material to produce higher pitched propellers in 11" propeller size class. Why does Solas stop the range at 17" pitch ?
It's quite hard to find original Yamaha propellers which have more than 14" pitch.
I'm planning do more testing after I have changed the engine mounting height, currently Selva is mounted to the lowest possible hole and it's producing an excessive rooster tail.
I would like to also test a stainless steel propeller with 16-18" pitch (semi-cleaver type).
My Selva 40 XS is a quite thirsty outboard, I noticed that a portable 30 liters fuel tank is not enough when doing longer cruises. Italian based Nuova Rade manufactures inexpensive plastic-like fuel tanks named Diablo.
I bought a 48 L Diablo series tank, actually the tank is a multi-purpose tank suitable also for water or waste and the hatch is packaged separately. The hatch is different for each purpose and for the fuel tank you get these parts:
The tank itself is white and looks like this:
I didn't get any installation instructions with the tank or the hatch so I downloaded those from the Nuova Rade's web site. I was a little surprised that the instructions were quite limited and didn't provide much details about what parts goes where.
I want to fill this tank in the same way as you fill a portable tank (just open the fuel cap and feed fuel directly to the tank). For my intended use I noticed two problems with the hatch, the first problem is that there are six holes and you get only four normal caps, one hollow cap is used to connect the fuel hose, this leaves one open hole.
The second problem is that the cap that covers the biggest hole (fuel input) is quite hard to turn and it does not have any "breathing" functionality.
For 48L tank you need to cut the black pipe in half in order make outbound fuel delivery line, fortunately there is already a mark where to cut it. The other black pipe is extra (maybe meant for diesel engines in order to pump diesel back to tank ?).
One mid-sized hollow cap was extra so I decided to use it to cover the sixth hole,
I noticed that you can put a quarter dollar there and with one O-ring it makes a perfect seal! ;)
A quarter dollar coin was used to seal extra hole.
In order to make the tank "breath" I drilled a couple of small holes to one of the smallest caps, this seemed to to work but on the water I noticed that some fuel was spilling out when the boat swang/jumped in the waves. The largest cap has 1½" threads and after lots of searching I found a perfect replacement cap from Plastimo, it also has an air screw!
Now the setup was complete and it has been working very well, I even installed a fuel sensor and a Wema fuel gauge. I never installed the red locking pin.
Plastimo cap allowed the tank to get replacement air.
According to Selva Marine you should use Champion L78 or Bosch W3AC spark plugs with Selva Madeira 40 XS. The 50 HP model uses the same plugs. Some matching spark plugs from other manufacturers are:
NGK B8HS
DENSO W24FS-U
MOTORCRAFT AE901RAC
I found a web site named MAGNUM Tuning which markets performance spark plugs and they have even listed Madeira 40/50 outboards!
I ordered two spark plugs and got these guys:
Racing spark plug for Selva Madeira 40 XS.
These "racing" spark plugs are manufactured by Brisk and the exact type is NOR14LGS.
MAGNUM Tuning states these benefits:
- Delivers 3% gain in horsepower and torque
- Notably improves throttle response
- Improves acceleration throughout the RPM range
- You can realize +5% fuel efficiency improvement
- Increases firing energy by up to 15% Flat spots cease
Brisk states this on their website:
"Our BRISK Premium LGS spark plug utilizes a very unique, semi-surface discharge electrode design. By implementing this design, the spark plug is able to fire a much larger spark plug gap, because the spark glides along the surface of the insulator, requiring much less energy than firing a traditional style air gap. Longer spark discharge makes more contact with the A/F mixture, igniting more molecules in the A/F mixture over a larger area."
My converted Selva 40 XS should produce 50 HP so with these spark plugs I could obtain something like 51.5 HP. Is that enough to make some difference ?
I installed the Brisk spark plugs and did a short test run. The engine started quite nicely, maybe a little eager than before. Unfortunately the engine stalled when I switched from neutral to forward.
This happened three times so I opened the engine cover and raised the idle speed, this helped a little but when I came back to harbour the same thing happened again (when switching from neutral to forward), my engine idle speed is quite high 1200-1300 rpms so this should not happen!
Brisk NOR14LGS spark plug being installed.
I cannot simply blame the spark plugs since the engine is running quite rough even with the stock spark plugs, maybe there is some problem with the air/fuel mixture or carburetor idle jets are dirty.
However with the stock spark plugs the engine has never stalled.
Anyway, I did some cruising with wide open throttle and didn't notice any speed gain, the sea was a little rough and thus the conditions were not perfect for accurate results.
I'm planning to do one more test in better weather conditions.
