Newbie questions on motors

[Frank C]

Vlad,

That Mercury Bigfoot 60 should be a great motor on your new boat. Collective experience on this forum would suggest your best choice is a 14" diameter prop at 11" pitch (USA sizing descriptions should be okay). Be careful on prop pitch! Since the larger 14" diameter prop is most common on much lighter weight boats, you frequently find only 13 to 21 pitch sizes, which are too much for the Mac. Be sure you ask for 11 pitch.

You are surely correct that boarding at the transom means danger for a swimmer. The 14" prop is no more risky or dangerous than the 12" prop (they are both deadly). Even in an emergency, the motor MUST be in neutral as a swimmer gets close to the transom.

My 26X has the optional swim ladder that mounts outside of (to left of) the port rudder. Even so, I never allow any approach to the transom until the motor is neutral or silent. I don't know if the 26M has an optional swim ladder like my X.

[Frank C]

Regarding a prop guard, or other prop enhancements, I feel that a prop guard device would not be sufficient to ease my concern over boarding safety. Otherwise, prop guards have mixed results, some advantages and some disadvantages. The Ringprop is now available for most Mercury motors, but they offer larger prop diameters (13" and larger) only in pitch sizes (18 to 21) that far exceed the capability of a Mac with 60 hp.

One member here, Alex, bought a ringprop for his classic Mercury (not Bigfoot) and later returned it due to unacceptable compromise on top speed. (Ringprop thread)

The only size the RingProp manufacturer makes (or made at the time) for the Mercury outboard is 10.4 inches diameter, and I bought a 10 pitch. Used it for about 6 months, never got full speed or RPM out of it, at least that size and pitch. West Marine took it back at full price LESS 20% restocking charge, and it was expensive to start with. $190.something, so I got a $160 credit - pretty damn good of them, I think. 'Course i am a preferred customer or whatever they call it.

I really like the design and idea of the RingProp, but it didn't perform on speed. The manufacturer's U.S. tech guy I talked to said not to expect as much top end speed as with a same pitch conventional prop, maybe a couple of MPH less. The tips of the blades are flattened off by that ring. Well with a true powerboat doing 30~60 MPH, maybe it wouldn't be much of a loss, but every MPH on a Mac counts, so that is where the problem is.

When I asked why they didn't make a prop that approximated the performance off a conventional prop at a given pitch, and rename the actual pitch to compensate, the guy said someone would have to get back to me. That was over a month ago. I don't think their engineers are working on sailboat props, with the special qualities we need, just high speed motorboats' props.

Now trying the 12.25 X 9 pitch Black Max Mercury brand prop, best results so far, but still need to raise the motor up and inch or two on the transom before finally deciding on the best numbers.

In an earlier thread when Alex first bought his ringprop, he had posted a picture of the prop AND a prop guard device. These prop guards are available in various designs, but they all contribute to drag, and owners seem usually disappointed by the speed demerits.

[Frank C]

Vladimir,

A note about "prop-sizing:" Moe was kind enough to ask me, in a private message, why I would suggest 11 pitch instead of 10 pitch. Prop selection is art rather than science, and a blending of others' experience with your own. It's my feeling that the 60 hp will be best with the 11 pitch, but I'm certain that my next suggestion would surely be 10-pitch (not 12-pitch).

You'll find that owners commonly speak of "maximum" prop diameter in reference to each outboard, as in "14-inches" for your planned Merc-60. However, prop manufacturers frequently do not make props to exactly those maximums. My Suzuki DF60 is using a 13.75x13 aluminum prop (means 13.75-inch diameter by 13-inch pitch). I KNOW that mine is "over-pitched" since it deters my motor from reaching Suzuki's top recommended engine speed, ~5,500 rpms. I also found that a Piranha composite prop, 14x12, was even worse (but composite, or plastic, props are not directly comparable).

So, I feel that your best "first guess" at a prop would be approximately 14x11 to attain the recommended max rpms. If the dealer suggests a 13x11 ... so be it! If you expect that your cruiser will be especially heavy, due to extra options or just extra fuel, the 10 pitch is also a good guess, used successfully by other M owners. But please ask your outboard dealer's advice, and also ask if they will exchange it for a different prop size if their first suggestion misses the mark. This "exchange privilege" is a common courtesy by USA dealers, maybe not elsewhere? Remember that you'll need to gather some operating time (20 hours or so) before you can really test the prop for maximum speed.

(Since the Mac is unlike most boats of similar size, don't be surprised if a dealer's first suggestion seems different than my recommendation. Your actual choice may well depend on the dealer's terms of sale and support.)

[Moe]

We have a 60HP BigFoot EFI on our 15' Whaler, and I would recommend a 10" prop for a 60HP BigFoot on a 26M. But that being said, I'd also carry a spare prop, so if you don't get it right the first time, you can relegate that prop to spare status. That's what we did with the 13-7/8" x 15" prop Whaler provided on our boat, that barely got the rpms into the recommended range with a light load. We switched to a 14" x 13" for most use when heavily loaded, when going to use heavy throttle, or when in heavier seas. For low-speed, part-throttle cruising, we sometimes switch back to the 15". It takes about 2 minutes to swap props and no cotter pins are involved.

Mercury makes special versions of their Black Max props for the BigFoots. They use soft, pressed in rubber hubs, designed to slip easier than their Flo-Torque hubs used for higher horsepower motors. The BigFoot props are painted silver, and their part number ends in A33, to distinguish them from the others, painted black with the part number ending in A45. They come with required washers and nut.



Some of the part numbers for the lower pitched BigFoot props are:

48-854340A33 14 X 9 pitch

48-854342A33 14 X 10 pitch

48- 77338A33 14 X 11 pitch

It's also not widely known, but Mercury makes a Flo-Torque III hub kit, PN 835257K 9, for using Flo-Torque II props such as the stainless Vengeance series on the BigFoot if prop rattle is a problem.

[baldbaby2000]

Chip,
I would go with the TLDI too if I had a choice. One thing I'm not sure I agree on is the noise. I've had both TLDI and carburated and didn't really notice a difference.

BB

[Catigale]

However, what you are doing in emergency cases, e.g., in the `man overboard' case?

We use the Lifesling II where one would motor to encircle the POB, then shut off the motor once you have the POB on a line, or get it attached.

No one comes near the transom while the motor is running.

I confess this has got me thinking about how I would get a POB in heavy seas where the engine is required...I would certainly address this first by taking extra steps to keep everyone on board - jacklines, etc..

[Dimitri-2000X-Tampa]

When I bought my 14x10 for my 50, the local Merc dealer specified a prop with the Flo-Torque hub. There is no rubber in it. I think the 14x10 is perfect for the 26X with 50 HP. A 14X11 would probably be better on my X boat if I had 60HP, unless I planned to power with ballast full and heavy load all the time.

[AJ]

Ihave the Merc 60 4stoke bigfoot, happy with it so far after about 100 hrs. I do get it serviced regularly. Turn the key and go! I had to experiment with props as no one here had any experience with the Mac at the time. Started with 14 by 9, way underpitched. 14 by 10 still a bit underdone. Had the 10 re-pitched up to 11 and is about right but still a little underdone. Motor will just hit 6000 rpm full ballast and boat loaded up with crew and gear. I reckon it could take 14 by 12 with no ballast and two POB. Best to pitch for full load unless you want to be constantly changing props. It is economical but will suck the juice at WOT. Unlike true planing boats the faster you go in a Mac the more fuel you will use. I budget on 1 litre per mile at fast 'planing' speeds, about half that at speeds around hull speed 6 - 8 knots. I can carry 100 litres.

I was also very concerned about the safety of the boarding location at the stern as well as general concerns regarding prop injuries. Had a nasty scare one day when some friends kids decided to jump overboard unannounced just missing the motor, running and in gear. I fitted a Prop Guard, sold here by Solas props (www.solas.com.au). These things are mandatory here for surf life saving etc. It's made of high impact plastic and produces a nozzle effect. With regard to performance I can't say that top end speed is noticeably different, perhaps slightly down (< 1 knot). Hits about 17 knots at 6000 rpm (20 mph, 33 km/hr), no ballast, flat water and 2 POB. Midrange grunt seems better. Manouverability is much better, can easily spin the boat on its own length with a bit of board down. Prop walk in reverse is largely eliminated (used to be a real pain) but reverse power is a bit less perhaps because of the nozzle resricting water inflow. I agree that a guard is not 100% effective but most injuries are produced by the prop brushing past producing a sliced salami effect which a guard will help prevent. Overall I've decided to keep it on.

Cheers,

AJ

[AJ]

Ihave the Merc 60 4stoke bigfoot, happy with it so far after about 100 hrs. I do get it serviced regularly. Turn the key and go! I had to experiment with props as no one here had any experience with the Mac at the time. Started with 14 by 9, way underpitched. 14 by 10 still a bit underdone. Had the 10 re-pitched up to 11 and is about right but still a little underdone. Motor will just hit 6000 rpm full ballast and boat loaded up with crew and gear. I reckon it could take 14 by 12 with no ballast and two POB. Best to pitch for full load unless you want to be constantly changing props. It is economical but will suck the juice at WOT. Unlike true planing boats the faster you go in a Mac the more fuel you will use. I budget on 1 litre per mile at fast 'planing' speeds, about half that at speeds around hull speed 6 - 8 knots. I can carry 100 litres.

I was also very concerned about the safety of the boarding location at the stern as well as general concerns regarding prop injuries. Had a nasty scare one day when some friends kids decided to jump overboard unannounced just missing the motor, running and in gear. I fitted a Prop Guard, sold here by Solas props (www.solas.com.au). These things are mandatory here for surf life saving etc. It's made of high impact plastic and produces a nozzle effect. With regard to performance I can't say that top end speed is noticeably different, perhaps slightly down (< 1 knot). Hits about 17 knots at 6000 rpm (20 mph, 33 km/hr), no ballast, flat water and 2 POB. Midrange grunt seems better. Manouverability is much better, can easily spin the boat on its own length with a bit of board down. Prop walk in reverse is largely eliminated (used to be a real pain) but reverse power is a bit less perhaps because of the nozzle resricting water inflow. I agree that a guard is not 100% effective but most injuries are produced by the prop brushing past producing a sliced salami effect which a guard will help prevent. Overall I've decided to keep it on.

Cheers,

AJ

[Catigale]

Prop walk in reverse is largely eliminated (used to be a real pain)

AJ- thanks for your post - Its nice to know that you can increase the safety of the prop with such a small effect on performance.

My first few seasons with the boat I really hated the prop walk, then a Kiwi taught me, in one long afternoon, how to use it to move the stern (obviously in only direction) where I wanted it to go. The next day I deliberately took a 'wrong turn' out our slip and ended up in a dead end, and then, (in full view of a crowd) used prop walk to 'back and fill' and spin the boat in its length plus a bit in between two finger piers.

I felt like the cop in those old movies ...."Nothing to see here people, shows over, move along...."



Marina owner was impressed



Admiral was impressed

[Catigale]

See the link on Back and fill

which is the name for this maneuver.....pretty easy...Centreboard should be down all the way.

[Rolf]

Both TLDIs I've owned have been completely trouble free, quiet enough to talk normal at 2000 rpm, and avg'd about 5mpg at cruising speeds (15.5 knots WOT on my old tldi 50, 3500 rpm on my almost 2 year old 90 tldi).

Enjoyed cruising up and down LA-Long beach harbor this past weekend in 80 degree weather and windless lake glass smooth conditions, WOT with one buddy aboard lightly loaded avging 22.5 knots! What a boat(26x)!
Rolf

[AJ]

Vlad,

The Prop Guard is a bit pricey but when you compare it to the cost of boat and motor as well as the numerous toys that all of us end up putting on these boats its not too bad. Solas imports them from the US (unless the factory has moved to China by now!) and the price quoted is in Oz dollars, about 70 cents US and includes sales tax. There are numerous different variations of guards on the market and Im sure you could source something locally.

My 10hp Evinrude on my 12ft tinny has a simple alloy ring around the prop as a guard (came with it when I bought it 2nd hand) and you could make something similar, but you would need to be good at metal fabrication. What I like about the Prop Guard is that it completely encloses the prop apart from the rear opening. You would have to stick a limb into the rear opening to damage yourself, the flow of water would tend to push things out (unless its in reverse!). I also like the bright red colour, which make the motor very visible when trailering.

I agree that prop walk can be useful when trying to spin large boats in tight situations. I found that it was pretty severe with the bigfoot and was often a hindrance when docking single handed. With the guard Ive found I can pull the stern in both directions equally well. To spin the boat I put the helm hard over and give the throttle a good squirt! This needs to be practiced without an audience and with nothing around to collide with!

I note youre more of a sailor and I can reassure you that the Mac is fun to sail. It will be more tender than you are used to (I think that adds to the fun!). They are not designed as a racer but you can make them get places in good time. My main tip would be to reef reasonably early (1st reef at 15 - 20 knots, 2nd at 25 - 30)and not to oversheet, particularly the headsail. Spent yesterday out with the family in steady 25 knots of breeze, 1 1.5 metre seas, number 1 heady and 1st reef. Managed to steam underneath a couple of 45+ foot ketches under full sail. They were no racing boats and long keel boats can be slugs to windward but the look on their faces as we smiled and waved bye bye (what the..!) was priceless!

Happy boating

AJ