Now for the Rest of the Story
I’ve just been reading the Dauntless thread on Trawler Forum. I appreciate all the thoughts, comments and suggestions.
I thought it would be appreciated if I detailed how and why I made some of the decisions I’ve made.
Crossing an ocean in a small vessel is always about planning and preparation, then the execution is pretty straight forward.
Now, while I did communicate via the Delorme InReach, there were a few issues that I saw no purpose in publishing. Why not? Because my Trawler Forum followers were concerned enough about routine stuff that I had well in hand. Telling everyone would add to their stress and not help me. Therefore man up and stay quiet.
So, let’s talk fuel.
Fuel or more pointedly, the amount of fuel this Kadey Krogen 42 needed to cross the Atlantic was the subject of a lot of debate.
In my mind there was no debate.
This debate had been settled two years earlier in crossing from Rhode Island to Ireland via the Azores. My average fuel consumption on that trip was 1.6 gallons per hour in far more adverse weather conditions. Having only partially refueled in the Azores, I arrived in Ireland with 50 gallons of fuel (and about 10 gal of water). I thought that was more than enough.
Summer 2015, in 4,400 nm of cruising, my fuel consumed was only 1.35 gallons/hour.
So, from the get go, I knew worse case 1.6, best case 1.2, most likely 1.4 gal/hr., which would give me arrange of 3,000 nm for a 2500nm trip. 20% margin.
But those numbers are not the whole story.
To understand fuel consumption for any given boat/engine/prop one must know the torque, power and fuel curves. The curves I use are in the next post. They tell me simply that max torque for the engine is 1500 to 1700, with 1400 to 1800, being slightly outside. So, I know where the engine is most efficient. Said another way, while I can slow down to further reduce fuel consumption, the engine will not be as efficient.
The next curve is the fuel curve versus speed-power and it’s an exponential curve. This means that a small decrease/increase in speed gives the Krogen a very big increase/decrease in fuel economy. Thus, instead of a single figure like 1.4 gal/hr., it data looks more like this:
So, with this information, I have strived to always keep the engine between 1500 and 1600, with my go-fast speed being 1700! At 2000 rpms, I’m at full afterburner and the engine makes all these noises, so I can only take it for a few minutes.
So, no matter what the conditions, I knew that I can always slow up to reduce fuel consumption. I actually think the boat could cross the Atlantic as I just did (with a following sea) at idle. It would take about 4 weeks, but only use less than 300 gallons of fuel.
Finally, on this passage, I arrived in Martinique with 110 gallons of fuel.
That averages to 1.23 gal/hr.
I actually think we should have arrived with about 130 to 140 gallons.
I determined that because I was meticulous about the time that each tank was feeding the engine. They had equal time, therefore they both should have the same about of fuel. The starboard tank has 30 gallons less than the port side tank.
The Fuel Leak You Never Knew About
Leaving the Canaries, with two full tanks, verified by my measuring the distance between the top of the tank and the fuel level. In each case, fuel was within ½” of the top of the tank. Now, it’s possible that the starboard tank had ½” less fuel to start, so that could account for 10 to 15 gallons but not more.
The first day underway I noticed fuel in the bilge. Fuel floats on top of water, so it’s hard to determine how much fuel we are looking at, a gallon or a cup?
With the rolling of the boat, water enters the scuppers and leaves the same way, but some water leaks down into the lazarette which then drains into the engine room bilge. In rough conditions, I’ve had enough water get in, that the engine room bilge pump has to pump about a gallon of water overboard every 5 minutes. In this case, it was pumping every 10 minutes, over the course of 24 hours, that’s a lot.
As Day 2 went into Day 3
, the amount of fuel in the bilge seemed to increase. Now for the first time I was concerned. I knew we had more than enough fuel for this trip. I knew we could even afford to lose a few gallons a day. But we could not afford to lose a gallon an hour or even half of that, at 12 gallons a day times 20 days = 240 gallons. That would be bad, very bad.
I could live with 120 gallons loss. I’d have to slow down more, but it would only add a day to the trip.
On each day, I looked at every fuel line, felt every fuel line I could touch. I could not figure how the fuel was getting into the bilge, though I could see it, or drips of it, running down the trough under the engine.
By Day 4, I was tasting every patch of moisture I could find in the engine room.
Oh, there were lots, as I had some seepish from the raw water impeller, some from the water heater relief valve, a significant amount from the stuffing box and now also from the rear lazzerette.
I tasted fresh water, salt water and sad to say some fuel. Not a lot, but enough. The more I looked at the bilge, the greener, (the diesel is green) it looked.
My prime suspect was a copper return line that did a “U” under the steel support for the engine. It was my prime suspect only because I could find no other source and while I could not confirm this was the problem, I was not able to cross it off the list either. I had also done the obscure things like closing all generator feed and return lines, since the return lines meet in a “T” before going into the tank. Therefore, it could be in the gen line, even without being in use.
On Day 5 we had an emergency appendectomy. Well, not really, but it felt like it.
I could not stop all the water from getting to the bilge, therefore I had no idea how much water versus fuel was being pumped out 10 times an hour. But I had to find out and if it was fuel, I had to save it.
I couldn’t turn off the bilge pump, but I could change where it pumps the water. I had 50 feet of 1” hose I had bought at Deevey’s in Waterford, Ireland because the price was good and I figured if I needed it, I wouldn’t be able to come back and get it.
I got a 1” nipple to connect two ends of hose. Then, the sawzall made quick work of the 1” bilge hose. I was also really pleased with myself that I remembered to close the thru hull valve, otherwise I’d have water flooding the engine room every time the boat rolled.
I hooked up 10 feet of new hose and we set it up to go into a 5 gallon bucket. Then each hour, we would pour off the fuel into another bucket and dump the water overboard. Thus, we would end up with a bucket full of fuel. We’d recover what we could, filter it and pour it back into the tank every so often. I’d also run the fuel polisher to further filter it continuously.
After our first 8 hours of this process, as I replaced Micah for my early morning watch, I quickly realized a few things:
1. This was day 5, no way in the world could we keep this hourly process up for another 15 days,
2. Our big bucket was clearly all water with just a sheen of fuel in it.
3. Our smaller bucket, that we had been pouring what we thought was fuel into, after 8 hours, there was about one inch of fuel on top of two gallons of water.
Making a command decision, I dumped the whole load overboard. At this point, it was clear that the fuel loss was on the order of a gallon or two a day at most, and most likely not even that. But also, the realization that this would be too work intensive for a two person crew. More on crew later.
In the next days, any sign of fuel totally disappeared.
Now one of my suspects, had been the overflow from the tank. But I had filled both tanks like this crossing the Atlantic the first time. At that time the port tank had leaked, the stbd tank had not. Having had the port tank resealed this winter, and the stbd tank never having leaked, it was not the prime suspect.
But as any sign of fuel disappeared, it became clear to me that what I was seeing was exactly what the port tank had done two years earlier. How did the fuel get out of the tank. Well, it seems, in one of the few build issues, the vent fittings in the tanks looked like after thoughts. Meaning that when we opened up the port tank to put the sealant in, there was an obvious rust stain under the fitting that had been screwed into the tank with sheet metal screws that had rusted out. Thus when the tank was full, as the boat pitched and rolled, there was pressure pushing some fuel out.
Two years earlier, leaving Nova Scotia the first 5 gallons got out immediately, but after that, it stopped totally.
This was more gradual, both at the beginning and end, but I am sure this is the reason. Nothing else would explain the tank leaking when full, but not later. Also, with these large following seas, the pitching was far more than normal for Dauntless. So with a strong pitching moment every 8 seconds, it seems that losing a few gallons of fuel every day for 5 days is pretty reasonable.
Looking back at my initial fuel consumption numbers that I determined after the first week, it is still not clear to me why it seemed that consumption was so little, in fact, the first numbers were half of what they should have been.
The only factor that is subjective in this process is me and my reading of the sight tubes. I have no flow scan. I don’t think one is needed. Had I had to really make a guess at any time as to the fuel use at any given point, I am sure I could do it within a tenth of a gallon per hour. No, I think the problem was I was not used to the pitching of the boat. And that pitching affected the sight tubes far more than rolling. And sitting here now, the more I think of that, the more obvious it seems.
The tank is over 9 feet long, but less than 3 feet wide. Therefore a pitching motion can have a much greater affect. I did not take that into account. The fact that the tanks have baffles that were strangely cut certainly reduced the effectiveness of the baffles and the sight tubes under those conditions.
Before I talk about weather below, there was clearly a surface current that pushed us along to a greater effect than even the knot current that probably existed. It could also just be the effect of how the Krogen surfs the waves, but at 1500 rpms, with both paravanes birds deployed, in flat seas the speed would be about 5 knots. Instead for that first week we saw 5.8 to 6.4 knots. That’s a lot.
One of the reasons I use gallons per hour and not mile per gallon, is that paravanes, seas, all affect the miles per gallon, but not gallons per hour.
So at 1600 rpms, the engine is using 1.5 gal/hr. If I throw in the paravanes birds, we slow by about a knot, but the fuel consumption does not change.
Below are the fuel and power charts I referred to.
The next posting will concern other stuff like weather, seas and paravanes