Trolling: Two Strokes or Four Strokes

[Icom]

What do you guys think of a Yamaha 50HP High Thrust 4-stroke (carburetor)engine for trolling?  Its fitted on a 14.5 foot boat.  I have never managed to calculate the fuel consumption for it.  Do you think that with low RPMs at trolling speeds I might have a sparking plug issue with carbon build-up?

[EmicMalta]

I had same engine but 25hp (4 stroke). I regret that I had sold it. 4 stroke engines are the best. As for trolling, i still think that does not give any problem, but depend on what kind of troling you will be doing. Your only problem is that with a 50hp, you can t lower too much the troling speed

[Icom]

Hi EmicMalta,  was thinking about the same thing.  Next time im out ill check out the least possible trolling speed.  I have a bad feeling about trolling with live bait as this requires between 0.5 - 2 knots maximum!  One other thing is that I most probably need to change the propeller as at WOT with trim up im only doing 4800RPM whilst the range for that engine should be between 5000 - 6000 RPM.  Reducing the pitch should get me into range and at the same time reduce speed at trolling speeds as there will be less cupping of water at low RPMs!

I stand to be corrected though.  Input guys on this pitch issue versus trolling speed reduction!

[Granitu]

Hi EmicMalta,  was thinking about the same thing.  Next time im out ill check out the least possible trolling speed.  I have a bad feeling about trolling with live bait as this requires between 0.5 - 2 knots maximum!  One other thing is that I most probably need to change the propeller as at WOT with trim up im only doing 4800RPM whilst the range for that engine should be between 5000 - 6000 RPM.  Reducing the pitch should get me into range and at the same time reduce speed at trolling speeds as there will be less cupping of water at low RPMs!

I stand to be corrected though.  Input guys on this pitch issue versus trolling speed reduction!

If it was my boat, I would invest in a kicker outboard for this type of fishing. - You need to put some serious trolling hours in a day to expect a catch nowadays (7+ hrs) and a 50hp would have issues with live bait trolling in my humble opinion.

[ciappinu]

I had a similar issue with a 50hp eTec. Maximum RPM was at 4900 with a 17 pitch prop. Reduced the pitch to 15 and now have around 5400 rpm. I had read that each pitch reduction increases RPM by around 300 but that is of course subjective. Boat performance is also slightly better in my opinion as the front lifts much less, however I might have lost 1 or 2 knots in maximum speed, which don't really bother me on a 14 foot boat as anything above 25 knots is uncomfortable.

[halop]

i troll good with my 50 honda efi as from 1 knot on 15 atom no vibration even when i go with long lines

[skip]

Setting your engine up to the correct WOT is extremely important and sadly people chase pitch, causing additional wear and tear, oil and fuel usage and more on their engines by being over propped.

ICOM, Aim for 5,500 with your typical load , which means you're looking at a 3-4 inch pitch reduction which is quite a lot. Indeed you will lose some bottom end thrust which should sort your slow speed issue, but listen to the live bait experts as the ultimate set up might well be using an kicker/auxiliary and a link kit to use the main steering on the kicker.