Optimal long distance cruise RPM's

[Ron Burgundy]

I'm starting to plan my spring/early summer 'toon expedition. I want to go to a island that is about 15 miles away (30 mile roundtrip).

Listed below is data from a Yamaha performance bulletin on a setup similar to mine. The range is based on 10 gallons of fuel.

I usually cruise at 4000 RPM because it just feels right. The motor isn't being overtaxed, but I still have decent speed.

My question is - What RPM do you recommend for long distance runs?


RPM MPH GPH Range
3500 10.8 5.14 51 miles
4000 13.4 5.58 56 miles
4500 15.6 5.57 56 miles
5500 20.4 3.85 39 miles WOT




I will have enough fuel with one full tank of gas, but I will bring extra. Should take about an hour to get there.

[IMHB]

I run a 22 foot Bennington with a 115 Yamaha on it.
When I cruse, I always set the throttle at 4000 rpm's
and like you said...it just sounds right.

I think you running at 4000 rpm's will get you there in a reasonable amount of time, and it's good for your motor.

Remember the rule of thumb for your fuel..
Plan on 1/3 of your fuel to get you there,
1/3 of your fuel to get you back,
And 1/3 of your fuel for an emergency.
This is the fuel just for traveling...to get there and back.

This is the minimum amount of fuel, it's always
better to take extra fuel, for running the boat when you get to where you are going.

Have a good trip.

HARRY

[GregF]

I have an 18 gallon tank and I would not hesitate to take a 15 mile trip one way when I had my 75 2 stroke.
We run down to Naples without giving it a second thought. How much fuel did you use when you went up to that island in Dunedin?

4000 does seem to be a good speed.

[Ron Burgundy]

I am actually referring to that island in Dunedin. It's named Caledesi Island State Park. I wanted to go last year, but it never happened.

If you look at this pic you can see a channel in the upper left that leads to a small marina. There is a place to eat so I want to go in the morning, grab some luch, take some pics, hang at the beach, then cruise back home.

[GregF]

Boat tanks are not that expensive, just get a spare and rock on. Just remember to rotate them so the gas doesn't get stale. Number them 1,2,3 (or whatever) and be sure you use them in order. Then it will always be FIFO using the oldest gas first.
Try to buy your gas about as fast as you use it so you don't have too much old gas sitting around.

[lakerunner]

4000 is best for me. Still quiet enough to visit and get down the lake

[GregF]

Pushing a boat through the water is a logarithmic function. You need a lot more power to get a little more speed.
Unless you have made your pontoons into planing hulls with strakes and the 3d log, your best efficiency will really be at hull speed, about 7-8 MPH. Because of the way 2 strokes work that might not be exactly true unless it is a small engine that is running at full advance but on a EFI 4 stroke it certainly is. Running legal "slow speed" I can run for well over an hour on a gallon of gas.

[Ron Burgundy]

Boat tanks are not that expensive, just get a spare and rock on. Just remember to rotate them so the gas doesn't get stale. Number them 1,2,3 (or whatever) and be sure you use them in order. Then it will always be FIFO using the oldest gas first.
Try to buy your gas about as fast as you use it so you don't have too much old gas sitting around.

I'm glad you mentioned this because it leads into another issue I wanted to ask about. When I bought the boat I was the third owner. The original owner disconnected the stock fuel tank because he said water was getting into the fuel. He added the 12 gallon red tank that you can see sitting on the deck in the photo below.

The guy I bought the boat from said he thinks it was just condensation that was forming in the tank, and that I should reconnect the original tank, and use the red one as a backup. I want to do this so that I have more fuel capacity, but want to make sure there isn't a problem with the original. Is there a good way to check a fuel tank for water leaks?

The original tank is located just in front of the transom...derectly below the deck where the red tank is sitting. The bottom few inches of the tank sit below the water line so maybe this is causing the condensation. The aluminium box with the white gas cap sitting next to the fishing pole is where the gas fill up is located. Shouldn't the water/fuel seperator remove any condensation that forms in the fuel tank?

[badmoonrising]

If the tank was a problem in the past, it may just need a cleaning. Is it removable ? Is it metal or plastic ? Metal tanks can and do corrode from the inside. Especially in these days of ethanol fuel.

The only way to check it for leaks is to remove it and fill it partially, then watch for leaks. Also a common failure point is the in-tank check valve, lots of times the tank gets blamed when it's the valve that goes bad.

The water separating fuel filter should handle normal amounts of condensation. Metal tanks are more prone to this than plastic ones.

[Ron Burgundy]

It's a plastic tank similar to the one below, but shaped differently. I don't think it is removable. At least not easilly. I don't really think the tank is the problem, but maybe water was getting in somewhere else. The guy I bought it from used only non-ethenol fuel. Can it be cleaned while still in place?

[badmoonrising]

It can be, but you'll get a more thorough cleaning if you can remove it. In the boat you'll have to use a siphon and be able to see inside the tank, looking for debris. You'll be amazed the amount of silt in the bottom of marine fuel tanks.

My old Proline had so much silt in it's tank it completely blocked the fuel filter. looked like sand (probably was). Gas station storage tanks aren't exactly the cleanest things, especially marina tanks. That's why Honda and other manufacturers add fuel filter strainers to their fuel fills, to keep the junk out of their products.

[Ron Burgundy]

I might call my local mechanic to see what price he wants to check out/clean the tank and reconnect it. I have found that it's usually better for me to work some overtime, and pay someone who knows what they are doing rather than screwing up something royally doing it myself.

[GregF]

If you can get to the fuel gauge sender that is a good access into the tank.
Siphon the gas out but DO NOT try your shop vac. It will blow up.
You can use one of those mop style toilet brush things to clean the crud out of the tank. You can tape a stick on the handle to get a better reach. One of those LED flashlights with the bendable whip is handy to see what you are doing. It is also good for inspecting the inside of the pontoons through a plug hole.

I ended up cutting a hole in the top of my console seat to get at mine. You put a gasketed hatch in there when you are done.
One source of water in the tank is the vent. Where is the tank vented? Can water splash up there?
The water separator is pretty much required no matter what you are running these days. I have the stainless Racor because the aluminum castings just do not last. It is rigged out over the motor bracket so it does get splashed.

[Buccaneer]

I used to live down in Pinellas County - over in Oldsmar - and I can tell you that Caladesi is amazing. The beach there has been named many times as one of the Top 10 in the USA. We used to put in at a marina in Ozona and loved to go to both Caladesi and a place called 3 Rooker Bar which is a small key a bit north of Caladesi.

3 Rooker Bar always seemed to have hundreds of sand dollars and other great shells if you are into that. Ask a local about 3 Rooker; it bacame my fav place to go to.

The snack bar at Caladesi is limited; we used to stop at Publix and get sub sandwiches, cole slaw, beer, and soda. =)

[Ron Burgundy]

Now I am even more motivated to go. I'm familiar with 3 Rooker Bar. Actually, if you go just a little but north you will hit Anclote Key and then a little bit further you will hit the North Anclote Sandbar. This is my local hangout. 3 Rooker Bar is about 5 miles south of the North Anclote Sandbar which is about 4 miles southwest from Gulf Harbors which is where my boat is docked. Did you move far away from Oldsmar?

I'm definately into the sand dollar thing...at least my little man is.