It's commonplace on these old school diesels to get the tach signal from the alternator. It isn't perfect, you have to adjust the tachs with the aid of a phototach aimed at the front engine pulley. We had to replace the tachs on Bella and calibrated them this way--they are reasonably accurate. I recently saw somewhere, maybe Northern Hydraulics, a tach for diesels with a digital readout that I think uses a phototach type pickup for very short money, I'll see if I can find it again, I was thinking about putting one on my old Fordson Diesel tractor which has a 3-153 Perkins--still runs great--and it's over 50 years old! Congrats on the new to you boat.
Does anyone here own a Gulfstar trawler?
- Thread starter Billylll
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In the manual section A, Ratings I see a 70 HP rating at 3600 RPM for light duty industrial applications. This conforms my suspicion that your engine may have been uprated and someone propped it accordingly.
Later on we will have to figure out if the props or governor limited that RPM.
PS I forgot to mention that if the tachs are correct even at high idle the engine should never have gone much above 3000 unless the governor was uprated. That 3000 RPM is fuel limited and set by the injection pump.
I am not saying there is anything wrong with this just explaining what you saw.
Later on we will have to figure out if the props or governor limited that RPM.
PS I forgot to mention that if the tachs are correct even at high idle the engine should never have gone much above 3000 unless the governor was uprated. That 3000 RPM is fuel limited and set by the injection pump.
I am not saying there is anything wrong with this just explaining what you saw.
I have been studying the manual the rating that Gulstar uses is max 58 hp at 3000 rpms. This seems like a good conservative number they are using. Since this is all new to me am I correct in my thinking? I seriously doubt I would run them above 3000 rpms for anything other than a short duration. But I'm back to thinking the boat was pretty lightly loaded only having 50 gallons of a 250 gallon diesel tank.
I agree the generator fuel burn is at 100% of rated output. I suspect it's a bit higher than many due to it's DC charging component? Most of the generators that are <10kw rarely have 50 amp alternators on them.
Bill
The thing to re member is that unlike gasssers diesels are governed. Doesn't matter what gs said. Your engines should not turn above 3000 unless they were uprated. Study the ratings and you will see that Perkins rates higher hp at higher rpms also governed limits.
Even out of gear they would be limited to 3000 so boat load doesn't matter until it gets so heavy that the engines slow because they are over loaded. Again there isno thing wrong but you have to think diesel not ungoverned gas
L
Even out of gear they would be limited to 3000 so boat load doesn't matter until it gets so heavy that the engines slow because they are over loaded. Again there isno thing wrong but you have to think diesel not ungoverned gas
L
In order for a diesel to run at 3,000 rpms loaded the unloaded (high idle) rpm's would need to be set at around 3,200 or so. Setting the governor this way will allow for the natural 'droop' which occurs between loaded and unloaded speeds which its typically in the area of 150 rpm's or so governor dependent.
Following a practice that most diesel owners feel will ensure a long engine life (including Tony Athens) you would want to be able to achieve your max loaded rpm's (3,000) plus 3-5% (3,090 - 3,150) on a hot and humid day when fully loaded as a brief test. If that rule is followed and you also cruise with a hp use less than 1 hp per every 2 cubic inches of engine displacement your engines should outlive the boat.
I would think that your unloaded rpm's of 3,300 is quite typical for an engine rated at 3,000 max loaded. It just so happens that they are the exact rpm's that my Hino's are rated at so I am quite familiar with the ratios.
Another rule of thumb is that a diesel genset will burn about 0.1 gph for every 1kw or power it is asked to produce. It is likely that your genset will use in the area of 0.5 gph for your practical use as you draw 4-5 kw as a typical higher average.
As a rough guess on main engine fuel use I would bet that you will be near 4 nmpg at 5.5-6 knots , moving to 2 nmpg at 8 knots and getting much worse at any speeds above 8 knots that the boat can reach. These guess's are inline with what I have realized in my 34 Mainship trawler as well as numerous boat tests on similar sized boats.
Hope this helps
Following a practice that most diesel owners feel will ensure a long engine life (including Tony Athens) you would want to be able to achieve your max loaded rpm's (3,000) plus 3-5% (3,090 - 3,150) on a hot and humid day when fully loaded as a brief test. If that rule is followed and you also cruise with a hp use less than 1 hp per every 2 cubic inches of engine displacement your engines should outlive the boat.
I would think that your unloaded rpm's of 3,300 is quite typical for an engine rated at 3,000 max loaded. It just so happens that they are the exact rpm's that my Hino's are rated at so I am quite familiar with the ratios.
Another rule of thumb is that a diesel genset will burn about 0.1 gph for every 1kw or power it is asked to produce. It is likely that your genset will use in the area of 0.5 gph for your practical use as you draw 4-5 kw as a typical higher average.
As a rough guess on main engine fuel use I would bet that you will be near 4 nmpg at 5.5-6 knots , moving to 2 nmpg at 8 knots and getting much worse at any speeds above 8 knots that the boat can reach. These guess's are inline with what I have realized in my 34 Mainship trawler as well as numerous boat tests on similar sized boats.
Hope this helps
I don't know what kind of injection pump is on a 4-154 Perkins, but on the 6-354 in our Mainship, the max RPM is actually printed on the tag on the CAV brand injection pump. Ours is 2700 RPM, and normal WOT under load is supposed to be 2450. We are underpropped, have seen as much as 2700 indicated on the tachs at WOT. Lots of variables, though, low water and air temperature can make a diesel make more power, saw the 2700 with a new coat of bottom paint, prop perfectly clean and it was in March with water temp in the 40's and air temp similar. There are several possible max RPM ratings listed in the engine shop manual, though. Might be worth a look on your Perks. My bet is that yours haven't been turned up, you are underpropped and that it won't matter much on a displacement boat. You'll be able to tow as big a dink as a you want with no worries.
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Great stuff Bill. I love my Portofino, but W1 for that money makes me salivate!
Best,
Paul
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This is the one I got on Amazon.
When I changed out from the analog VDO tachs to the digital floscans, it showed I was absolutely 100% dead on accurate with zero deviation.
And all for $20.00 including some reflective tape!
As a result, I just had my props done at Propscan.
http://www.amazon.com/dp/B001N4QY66/ref=pe_385040_30332190_TE_M3T1_ST1_dp_1
RWS
When I changed out from the analog VDO tachs to the digital floscans, it showed I was absolutely 100% dead on accurate with zero deviation.
And all for $20.00 including some reflective tape!
As a result, I just had my props done at Propscan.
http://www.amazon.com/dp/B001N4QY66/ref=pe_385040_30332190_TE_M3T1_ST1_dp_1
RWS
Everyone is making great comments/ I'm new to old school diesels so bare with me.
I'll find out what type of injector pump is on the engines once I return. I will look for the tags everyone is mentioning. I just learned these engines (with different cooling) were used in Mazda trucks in Australia. The engines seem to have a pretty good reputation for being reliable. Smitty your fuel burn numbers are close to what the owners manual says that came with the boat.
This boat unlike the Mainship 34 has a real displacement hull so I'll never hit the speeds the Mainship 34 MarkI-III's will do and putting similar horsepower into her wouldn't be a net gain. Then again I am not buying this boat to install new motors in it. It appears the Perkins 4-108 and the 4-154 have more in common then the 4-236 engines.
As I mentioned earlier I'm quite happy I have the smaller 4-154's.
I do have 2 strange AC units on the boat they don't work they look like a window unit but the fan motor is also the raw water circulation pump. Do I throw these away or can they be repaired? Anyone ever seen one of these strange looking marine AC units?
Bill
Not the one's seen in the rear salon but below in the forward birth and the aft stateroom. They look like window units but they are water cooled. The instructions say to prime the pump by initially running the fan only then engage the AC after they have primed. Right now they just hum the fans don't come on.
Bill
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Bill, I think Micheal knows what the name of those AC units is, but I can't remember what brand name he told me. I remember them being out of PA and I'm thinking Reading. That would match up with http://marineair.com/ (now owned by Dometic, of course!). My 2 cents is that since you already have the enclosures I'd look into replacing the insides with self-contained water-cooled units if they can't be repaired. Here's a picture I took if anybody recognizes the unit:
