Fuel Consumption Volvo 29hp

[a64pilot]

Originally Posted by Sid at SailAway

Here's where I pulled the numbers. I cruise at 2800 using one engine and make 6 knots. I've made so many fuel checks that I'm pretty confident in the .625gph burn at 2800rpm. I'm still confused as to how Cotemars chart can be so far off. Cotemar, thoughts? That's basically double what I burn.

I'm going to go out on limb here and suggest that 500 to 800 RPM from max attainable RPM is a suggested maximum cruising RPM, not a suggested cruising RPM?

Meaning a don't turn her faster than that or you will hurt it, not a run her at 500 RPM short of the redline all the time, cause that has to shorten the life?

[TrentePieds]

Recently there was discussion showing pretty conclusively that the HP required to drive a mono at hull speed of 7.5 is twice what is required to drive the same hull at 5knts, thus fuel consumption is double, or near enuff.

I shouldn't doubt that a cat being forced could burn 1 1/2 times the qty I calculated, a qty that agrees with most other people's opinion.

TrentePieds

[Cheechako]

Fuel gages are notoriously bad. Don't trust them.

[Sid at SailAway]

Originally Posted by Cotemar

Sid at SailAway,

At 2800 RPM your pretty much running at MAX RPM for a Volvo Penta D1-30 (30hp)

I have no idea what motor you have and what your specs. are.

The spec's I am posting are the ones the OP is asking about. for a Volvo Penta D1-30 (30hp).

That's where the discrepancy is. You have a D1-30 which makes 20hp, according to your fact sheet, and I have the 2030 which makes 29hp. The OP states that his Volvo has 29hp so I'm assuming it's a 2030.

[Cotemar]

Originally Posted by Sid at SailAway

That's where the discrepancy is. You have a D1-30 which makes 20hp, according to your fact sheet, and I have the 2030 which makes 29hp. The OP states that his Volvo has 29hp so I'm assuming it's a 2030.

You may want to check that fact sheet again as the D1-30 makes 28.4 hp
Do you think that .6hp would give you that much different fuel usage.

28.4hp and 29hp would not be that much different and the newer engine would most likely get better fuel usage.

[JasonS]

Congrats on the Manta purchase!

We have a 1999 Manta 40 with Volvo D1-30's as well. The fuel/water gauges are not accurate. We've replaced with new one's and still can't get them to be accurate.

We typically motorsail on one engine at a time - at 2400-2500 RPMs they burn roughly .5 gallons/hour. Your fuel tank is likely on the starboard side under the aft seats. There's a panel in the floor that's removable and the fuel tank is underneath. You can open one of the spare tank fittings on top of the tank and take a long stick and gauge how much fuel is left. That's the easiest/cheapest way.

Make sure you join the Manta forum if you haven't already.

[Sid at SailAway]

Cotemar, my bad, I was looking at the kw side of the spec sheet.

[Dod42]

I have always found this useful. Doesnt list every engine but does seems fairly accurate for those listed. On our Lipari I did calculate the fuel capacity per millimeter, so I made a dip stick so I could dip the tank at the start and end of a trip. In our case it is 8.82 litres per cm measured from the bottom.

Volvo Penta Diesel | D1 20 & D1 30 | 20 / 30 hp | Fuel Consumption - Liters per hour

[Cotemar]

Dod42,

I like your web link also.
Just wish they had the Volvo Penta D2-55 listed.

[yachttie]

Can he dip the tanks? I always do a dip if not sure. Gauges can be notoriously innaccurate.

[savoir]

If anyone wants a fuel gauge that really works I can recommend the Tank Tender. The same unit can also measure your water tanks.

Hart Systems - Home

[Rufduck]

Coatmar is right but only posted half the picture. Max rated rpm is 2800-3200. Max torque is near 2000 rpm and Volvo states the D1 was designed as a lower reving engine that cruises at 1800-2200.
Just finished a 1500 nm delivery and 0.5 gallons (US)/hour at 2000 rpm per engine was very close to our computed fuel burn. This was motor sailing with port, starboard or both engines running. Sailplan was kept conservative per the reefing schedule in the sailing manual. Average speed was near 7.4 nmph (knots). That is nearly 15 nmpg.
btw, running both engines increased speed by perhaps a knot, maybe a knot and a half and jacking the rpms to 2800-3000 made a trifle more.
Compute the hull speed...it's about 7.4 knots and you are way into the area of diminishing returns.
In all my reading, I've never seen a Volvo recommendation to cruise the D1-20 or -30 engine above 2200 rpm. From the torque curve, it appears to have been designed for the 1800-2200 range.

Cheers, rufduck