[Dliguori25]

<div><span style="font-size: 10px">Hello</span></div>

I recently purchased my first ocean boat, a 1990 Tiara 33' (re-powered with 8.1L Crusaders in 2006). On my sea trial one of my biggest concerns was if the fuel consumption would be so high that I would think twice about using the boat, so I was pleasantly surprised that the Floscan Twinscan was showing about 20 gph (10 per side) at 22-24 kph. I figured since I'd mostly be using it for Catalina trips that my gas bill would be below a grand and I could swing that without much concern. Well, this weekend I got my first trip in and I was a bit shocked at how off these calculations were, particularly when I had to fill up again in Avalon at $7.20 a gallon! (Joke is on them though since I accidentally took their $5 gas cap key) After spending $1080 for 150 gallons just to get back to San Diego it dawned on me that it would take just approximately 35 trips before I spent more on gas than I did on the boat. I left San Diego with close to a full tank (295 gallons I believe) and arrived in Cat with less than a quarter tank, burning approximately 200 gallons. I had expected to arrive with well over a half a tank since since it's only about 80 miles from my home to Avalon. Granted we brought a 7.5' dinghy mounted on the swim platform, a kayak, two paddle boards, and 3 people, so we were fairly loaded up. This was a pleasure trip doing about 22 kph on the way there with medium seas (not big but pretty rough). On the way back I had to keep the power in a bit further because when riding up the back side of the swells it was losing revs so it fluctuated between 3200 and 3800 rpm depending on if I was riding up or down the swells.</p>

Okay, so I guess the question I'm getting at is, does this sound right to you guys? Should it take 350+ gallons to get a 33' Tiara with 8.1L engines from San Diego to Catalina and back? Can my flow meter be off by that much? I feel pretty stupid now for having made the mistake at sea trial of assuming the Twinscan was accurate. Because on the trial we weren't going a calculated distance from point A to B i didn't have any way of determining fuel consumption aside from the floscan. I didn't think I was getting into this boat with my eyes closed but now I'm wondering if I was kidding myself thinking that I could afford Catalina trips a couple times a month.

On a side note, while writing this I went down to the boat and when I stepped from my dock to my swim platform the step down felt bigger than normal so I turned on the bilge pump and opened the generator hatch and was shocked to find about 100+ gallons of water in the bilge. Fortunately the bulkhead kept it isolated to this compartment but I'm concerned that the generator my be damaged as the water was above the bottom of the generator. I found that my fused float switch, which I replaced just a month ago, had a blown fuse. I'll be adding another switch and pump to make sure that a 10 cent fuse doesn't wreck my generator, underwater lights, autopilot actuator, etc, in the future, if those items aren't wrecked already from this. There was water dripping from the through hull fitting that deck water gets channeled through, and which is normally above the water line unless the ass end is sinking, as it was. That of course doesn't explain how it took on enough water to get that through hull under the water line. I think I may have a leak in my freshwater system as I seem to run out way too fast - ran out this weekend and we didn't even use the shower. That could explain it, though my tank is between my engines and the only line that goes into the generator compartment/bulkhead is the transom shower. I'm embarrassed to say that aside from checking the oil before the trip I never opened the hatch while in Catalina. I ran the generator a bit even on the day we left so I don't think this was the cause of my poor gas millage but it might account for why the motors were bogging a bit while riding up the back side of the swells on the way back. In either case I'm just a tad flustered that so many things have gone wrong on my first trip and I'm seriously considering selling the boat as I don't want to spend $2k everytime I want to go to 80 miles to Catalina for the weekend. I'm not new to boats but I've only owned ski boats before so I'm new to generators, marine AC systems, and other complexities that a trailered ski boat does<span style="font-size: 10px">'t have, so forgive my ignorance here.</span></p>

There's more but I should leave it at that since I already wrote a novel here. Thank you SOOO much in advance for any advice you can lend as I'm feeling really over my head all the sudden and this first trip in my cozy boat has uncovered many items that need addressing.[img]../images/emoticons/worthy.gif[/img]

Thanks!

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[Uhehner]

We did 1200 miles on 1000 gallons with a 36 convertible with 8.1 Crusaders. You have some troubleshooting to do. Maybe repack the shafts with GFO packing for starters. Capt. George

[Dliguori25]

Thanks for the reply Captain George! I did a little more troubleshooting and just updated my post. Looks like my freshwater tank is leaking and must be what flooded my generator compartment. Since I left my pressure pump on a lot of the time we were there it must have slowly dumped the water into the bilge. I have dripless shaft seals, not suffing boxes - can those leak over time?

So to you it sounds like I should in fact be getting the sort of fuel consumption that my floscan is telling me I'm getting then? Well that would be a relief, although it adds some confusion. I was basing my speed off my GPS SOG and was above 20 the whole time, so I should have got there on less than roughly 85 gallons, but apparently burned more than 190. There must be something that I'm misunderstanding or miscalculating.

[Dliguori25]

Does anyone else have any thoughts about my fuel consuption issue? I determined that the bilge water came from the port rudder shaft packing - it's leaking a steady stream but unfortunately I can't seem to tighten or loosen the fittings as there's quite a bit of tarnish and it's on pretty good. I can't spray any PB Blaster on it as it immediately gets flushed out so I plan to work on it next time I get the boat hauled out. For the time being I'm giving my bilge pump a lot of exercise and I'm in the process of adding a backup 2200 gph johnson bilge pump so if I blow a fuse on the main float switch again I have the Johnson pump and separate float switch there for backup, connected directly to the battery.

Back to the matter at hand - I now know why I took on so much water and that certainly explains why I burned so much fuel on such a short trip, HOWEVER, it doesn't explain why my Flowscan TwinScan was showing 10gph per side when in fact I was burning more than double that. Any ideas folks? Maybe I'm missing something but it seems like despite the extra 2k pounds of water I brought with me in the bilge, that should be reflected on the flowscan?

[Dliguori25]

BTW, could the moderator please move this post to the general or maintenance forum since I probably shouldn't have specified it to the Open forum? Or better yet, delete it and I'll post a new one that is more accurate and up to date with my investigation of the leak? Thanks Moddy!

[sawdustdad]

I had a 1988 3300 open with carbureted 454s, and I got .6 to .75 mpg at 19-20 knots and 3100-3200 rpms. You pay to play with a boat.

[Chris Burkard]

Flo-Scans are notoriously inaccurate and their accuracy is highly dependent on the installation. 3000 to 3200 RPM is approximately the sweet spot for those engines with that hull on a calm day. If the engines are tuned properly and the bottom is clean and you have the correct props, you should be getting about .87 MPG. It is extremely unlikely you are getting over 1 MPG. I have never seen it in a boat that size with those engines. If you run slower than 3000 RPM, your MPG will drop as the hull drops lower in the water and comes under more drag. Faster than 3200 RPM and your mileage begins to drop as well.

Now, .87 MPG is under ideal conditions. If you run into 14 knot winds with a 3' swell, your MPG may drop to .70. If you are running in 5' swells with a bit of chop, your MPG may drop to .5 MPG. If your props or bottom or dirty, you will burn more fuel. If your engines are not tuned properly, you will burn more fuel. If you have the wrong props, you will burn more fuel. If you overload the boat with extra weight, you will burn more fuel.

The other issue is the 33 never came with 8.1L Crusaders. The original engines were 7.4L Crusaders at 320 HP each. The 8.1L engines are likely the 385 HP versions (the 8.1L is also offered in a 425 HP version) and have a completely different torque curve. What propellers do you have? The original props for the 7.4L engines will not work for the 8.1L engines. Wide Open throttle, what RPM are you achieving? Those engines should turn between 4350 and 4550 with a fully loaded boat. If they don't turn up, you likely have the wrong propellers and are overloading the engines burning extra fuel.

Did you survey the boat before you purchased it? It sounds like you have quite a few issues that should have been discovered during the survey.

E-mail me and I will send you a performance report for a 31 Tiara with the 8.1L engines. It is not a perfect match as the 33 is wider and heavier, but it will give you a general idea of what the fuel burn should be at various RPMs.

[Chris Burkard]

I was unsure whether to mention this or not, but I will. Diesel engines are much better for open water cruising. They are less weight sensitive, meaning a few hundred pounds of extras will likely not result in extra fuel burn. They are also less sensitive to sea conditions than gas engines. The additional loading caused by waves and wind have less of an affect on fuel efficiency. Diesel engines burn less fuel to push a similar sized vessel the same distance. A 33 Tiara with Cummins 315 HP diesels at 27 Knots in calm conditions would get approximately 1.35 MPG. Diesel is a better choice (inboard boats) for open water offshore cruising. Gas is fine for inland water, lake and river use.

[mikefromlb]

I have a 1989 3300 Open with the same Crusader 8.1 L Engines, new in 2005, that I purchased in San Diego 1 year ago. Keep it in Long Beach. Comparative fuel usage: travelled San Diego, Shelter Island to Long Beach, with full tank 395 gals. 6 hours, about 100 NM, ran 2800 RPMs, relatively calm seas in June, 16 - 18 mph and had the bow fully trimmed; arrived in LB with fuel between 1/2 and 3/4 tank full.

3 weeks ago, did LB to Catalina and return- started with 3/4 tank - rough seas both directions, fished backside in rough water and front side in calm. Total 95 NM over 2 days. Lots of slow trolling. Used 85 gallons of fuel. Crossing at 2800 - 3000 RPM's. Speed was all over the place due to swells on crossing.
Recently replaced both Risers and Manifolds on both engines. Currently at 700 hours on the engines.
Cat trip was 3 guys and a full bait tank on this trip.
Hope this helps? Happy to trade issues with you. Email me at: mikefromlb@icloud.com. Mike