Weather "Window" Advice Needed/Wanted

[psneeld]

One of two things: They believe they are the stand-on vessel “engaged in fishing” or as has been told to me by more than one rockfisherman, they don’t know the rules of the road and they don’t care.

My experience is they are for the most part "I dont care " types. They could easily back off just a few degrees to avoid a lot of near misses...but they dont....even when you do ( and you are the stand on vessel ).

 

[stroutmail]

Arrived at home port. Last leg was Annapolis to Port Deposit on Susquehanna River. Cloudy, overcast and wet..choppy waves direct on bow were not uncomfortable.

Experienced the "tide and wind in different direction" chop people described as common on Chesapeake.

The GB 36 is pretty comfortable with waves and wind from any direction other than on the stern at an angle..i.e. "quartering". I did not mind the roll, or the porpoising bobbing, but the yaw caused by forces pushing the low deadrise stern around was not comfortable. It was like my inner ear was OK with two axis rotation, but became overloaded with rotation on three. Effect probably varies alot by resistance to vertigo..car sickness..or seasickness.
I am tolerant if I can anticipate movement, but unanticipated movement can get to me over a long period.

Overall, a great "orientation" voyage...very comfortableand acclimated with the vessel in various conditions. Really a good boat..used no oil in 30 hours running, and burned very little fuel. (Have not calibrated tanks, but we used less than three inches on site glass) Very economical at $1.45 per gallon.

 

[O C Diver]

Glad to hear everything worked out. Did the captain end up being a good pick?

Ted

 

[oguidry]

I previously owned a 1989 GB36 with twin Cummins 6BT5.9Ms.

I figured one inch on a tank was six gallons by using the tank dimensions.

Based on that assumption, you used about 36 gallons.

I placed a self adhesive tape next to the site gauges to facilitate the measurements - https://www.rockler.com/self-adhesive-measuring-tape

 

[stroutmail]

I previously owned a 1989 GB36 with twin Cummins 6BT5.9Ms.

I figured one inch on a tank was six gallons by using the tank dimensions.

Based on that assumption, you used about 36 gallons.

I placed a self adhesive tape next to the site gauges to facilitate the measurements - https://www.rockler.com/self-adhesive-measuring-tape

Great idea..thanks. Very impressed with such good fuel economy. Some of the time was running slow in the ICW and approaches, but probably running close to 2 gallons per hour at cruise speed. I need to check accuracy of tachs, but we were running between 1700-1900 rpm and hitting speeds on GPS of 7.5 to 9.5 mph. Less than $30 day fuel cost for typical cruising.

 

[stroutmail]

Glad to hear everything worked out. Did the captain end up being a good pick?

Ted

I would use Dustin Daniels again under same conditions...unfamiliar boat and waters. Very skilled, conscientious, and personable. Exceeded my expectations. What would have been a stressful single handed trip was quite pleasant and I learned alot. Accelerated my learning curve for the boat.

Another advantage that was a pleasant surprise..the marina gave us VIP treatment since he is a regular customer.

 

[mvweebles]

Great idea..thanks. Very impressed with such good fuel economy. Some of the time was running slow in the ICW and approaches, but probably running close to 2 gallons per hour at cruise speed. I need to check accuracy of tachs, but we were running between 1700-1900 rpm and hitting speeds on GPS of 7.5 to 9.5 mph. Less than $30 day fuel cost for typical cruising.

At those speeds, your boat is likely burning 1.5 to maybe 2.0 gph. Much above 8 kts and fuel burn will ramp up to 3gph.

Again, congrats. Gb36 is a sweet boat.

 

[AUXOPdwp]

Great idea..thanks. Very impressed with such good fuel economy. Some of the time was running slow in the ICW and approaches, but probably running close to 2 gallons per hour at cruise speed. I need to check accuracy of tachs, but we were running between 1700-1900 rpm and hitting speeds on GPS of 7.5 to 9.5 mph. Less than $30 day fuel cost for typical cruising.

The Fuel stats below were derived by Sabre in 1991 for publication in the loose leaf bound Users Guide. My 1997 boat (purchased Nov 2018 with 1000 hours) matches these numbers very well, except at the high end, because my boat tops out at 2450 RPMs, which is of great concern. Cummins GURU Tony Athens explains (www.sbmar.com) why the installed engines MUST reach 2700 RPMs at WOT, if they're to live full lives - over versus under propping is the issue, hence I can't determine if I'm propped correctly.


I've determined that my 2450 limit is due to a set screw limiting throttle travel, rather than the governor setting on the Glendinning synchronizer. Too many people fail to understand the damage they do by warming up or continuously running at low RPMs, rarely if ever running WOT. Some can't afford the fuel burn, others haven't learned how to properly operate & maintain a diesel as taught in Tony's Tips - Seaboard Marine. I hope to have a mechanic adjust it this summer, since I'm afraid to possibly get involved with tricky Bosch fuel pump adjustments.


Sabreline 34 Fuel Burn w/ twin 6BT5.9Ms


RPM MPH Knots Total-GPH MPG NMPG Est Usable Range (10% Reserve)

1000 7.1 6.2 2.0 3.57 3.10 802
1250 9.2 8.0 2.9 3.17 2.76 714
1500 11.6 10.1 5.0 2.32 2.02 523
1750 12.5 10.9 7.8 1.61 1.40 362
2000 17.8 15.5 10.8 1.65 1.44 371
2250 22.9 19.9 14.7 1.56 1.35 350
2600 27.6 24.0 19.5 1.42 1.23 318



I have parts and service manuals for the engines if you need info. Meanwhile you can also relish the fact that you don't have timing belts, like Yanmar.

 

[stroutmail]

This thread is not intended to open the can of worms regarding controversy about running at RPM below WOT or max load. That said, I am very skeptical of any so called "guru" who claims you have to reach max governed RPM to reach max engine life. There is a lot of scientific literature on this subject...most agreement is: extended operation below 50-60% load causes carbon/soot buildup that does shorten life. Hull speed, best fuel economy load is often in that 50-60% load, so it is prudent to vary the load, which generally means running above hull speed (but not necessarily WOT max designed RPM) part of the time. The goal should be for cylinder temps to be high enough to avoid/eliminate carbon buildup. On my trip I limited idling, and varied RPM from 1700 to 2100 RPM. My calc roughly estimates 2100 rpm (10 mph) is around 80-85% max power.

Very few engine designers would recommend constant max rpm or max load...nor would they recommend extended low load operation. I am old enough to remember the 1970's when Cummins recommended lower RPM to improve fuel economy..older fleet managers argued engine life would decrease..engine life improved. Then engines got bigger with much high HP..so running at much lower % of max for long periods...engine life kept getting better.

My little single 120 HP engine gets well exercised. With twin engines, running low speeds does use less % of max HP, so many are running below 50% of engine capacity for extended periods which does risk increased soot/carbon accumulation.

Engine load is mostly determined by boat speed and less (very little) by RPM. A 36 ft trawler maybe only needs 70 HP to run hull speed. So, with two engines together totalling 250-300 HP, to run at 70% load, you need to run higher speeds..and use more fuel.

 

[rslifkin]

Sensitivity to running at light load, being overpropped, etc. all varies widely between engines. Some are more prone to sooting up under light load, while some are fine with pretty much anything more than idle. Prop wise, some engines are fine with a bit of extra load at lower RPM provided you don't push it to the limit while overpropped. Others are more sensitive and will live longer if propped to reach or exceed rated RPM to keep the load lighter at lower RPM. So there are rules that are pretty much universally safe to follow, but not necessarily gospel for all engines out there.

 

[Sax]

We have a 42 Grand Banks Classic and live on the bay in Poquoson, VA. We just came south last week with 10-15 on the beam and had a really uncomfortable ride on our boat. You don’t get “rollers” on the bay, just short, steep waves with little interval between them. Because the bay is so wide in the south and so shallow everywhere, it is difficult to impossible to get close enough to shore to really block the wind. We will go with 15-20 on the forward quadrant, but that is not a pleasant ride. Grand Banks trawlers get their sterns pushed around a lot in following seas, so we use 10-15 knots as a guide on that quadrant as well. Steady winds above 15 knots on the lower bay in any quadrant will produce a ride you will not enjoy in your GB. The eastern shore has some great ports, but most are well off the bay or up rivers. You will find more safe harbors coming up the western shore.

 

[AUXOPdwp]

This thread is not intended to open the can of worms regarding controversy about running at RPM below WOT or max load. That said, I am very skeptical of any so called "guru" who claims you have to reach max governed RPM to reach max engine life. There is a lot of scientific literature on this subject...most agreement is: extended operation below 50-60% load causes carbon/soot buildup that does shorten life. Hull speed, best fuel economy load is often in that 50-60% load, so it is prudent to vary the load, which generally means running above hull speed (but not necessarily WOT max designed RPM) part of the time. The goal should be for cylinder temps to be high enough to avoid/eliminate carbon buildup. On my trip I limited idling, and varied RPM from 1700 to 2100 RPM. My calc roughly estimates 2100 rpm (10 mph) is around 80-85% max power.

Very few engine designers would recommend constant max rpm or max load...nor would they recommend extended low load operation. I am old enough to remember the 1970's when Cummins recommended lower RPM to improve fuel economy..older fleet managers argued engine life would decrease..engine life improved. Then engines got bigger with much high HP..so running at much lower % of max for long periods...engine life kept getting better.

Sorry to have sent the wrong message. Of course the load should be varied, etc. You describe proper operation well but the joker is how to confirm it.

I've been under the impression that you would appreciate insights concerning your new trawler & 6BT5.9Ms, as I have been for the past 17 months. I offered you the single most valuable source I've found. If you scrutinize Tony Athens website, sbmar.com, you should be very impressed with his business of 30 years & knowledge. He is famous for solving users puzzles on boatdiesel.com and other forums, for many years - and for fostering superior after market subsystems like our engine's raw water pump, or the EnviroVent CCV system.


I too look at Cummins charts and 'imagine' that I'm loading my mechanical (not electronic) engines properly. Yet the only way to gauge such, is to achieve correct RPMs at WOT, as shown here: https://www.sbmar.com/articles/propping-cummins-mechanical-diesel-engine/
To avoid further distorting this thread, I'll offer no further advice unless you ask. Best of luck.

 

[stroutmail]

Here is a short youtube of the three day trip that was the subject of this thread.

First Day (Norfolk to Deltaville) Forecast 2-3 foot waves from SE--15 mph winds, gusting to 20 from the East.
Actual was different---more calm at first, then crossing York River outlet, tide changed and waves picked up and became more choppy at the York Spit. Unpleasant. Happy to arrive in Deltaville.

Second Day (Deltaville to Annapolis) 5 mph wind tide on our back most of the trip. Very smooth until Annapolis approach area were waves from speed boats made it very choppy.

Third Day (Annapolis to Havre de Grace) Rainy, 10 mph wind on our nose, tide on our back, really good ground speed (10 + mph). No rolling, but porpoising quite a bit. Pleasant.

 

[RT Firefly]

Greetings,
Mr. s. Excellent. You're laffin'.