Cutwater and Ranger Ventilation

[ixlr8]

And with 50+ years on the water and having been aboard literally hundreds of boats, the only ones I've ever seen with forced air ventilation(and let's face it passive systems are ineffective) in the engine space have been large commercial vessels.

The Sabre boat I help build has four 15" diameter fans for venting the engine compartment. They are temperature controlled, if the temps get too high... the fans come on. They move a lot of air and are fairly noisy. There is about 8 sq ft of air inlet, I don't remember the size of the outlets. The boat is running with two 900 hp Volvo turbo diesels. Vague memory from talking with the designers is the temperature setpoint was determined based on Volvo specs.

 

[BB marine]

The last 20 plus years marine manufactures have put more effort in ventilation of engine compartment. EPA requirements of reduced emissions started increasing marine engines operating temperatures. With the increased operating temperatures of power plants increased the compartment temperatures. Power ventilation is standard equipment Gas and now is common in diesel powered pleasure craft. Engine manufactures have specifications that need to be met to provide maximum performance from their products. There is a complete section in the Volvo engine installation manual sizing passive and power ventilation to meet the requirements. I was on board a 37 Nordic Tug, engine room has power ventilation, I have been looking at a Helmsman 31 comes standard with power ventilation. All manufactures use passive venting in and Passive venting out, many are now using power venting. Ranger/Cutwater Passive in thats it.

Just as an aside, in my youth I worked on boats built for Gulf coast oil field crew relief service. When we wanted to squeeze every bit of HP that we could out of the old Detroit two strokes we would open the deck hatches directly over the top of the engines so they could breath.

Thats what the Volvo Rep told me to do. Run with the deck hatch open !!!

The Sabre boat I help build has four 15" diameter fans for venting the engine compartment. They are temperature controlled, if the temps get too high... the fans come on. They move a lot of air and are fairly noisy. There is about 8 sq ft of air inlet, I don't remember the size of the outlets. The boat is running with two 900 hp Volvo turbo diesels. Vague memory from talking with the designers is the temperature setpoint was determined based on Volvo specs.

There is a lot of money in that compartment, Why not run the engines in the right conditions? Sabre followed the Volvo Installation Manual.

 

[ixlr8]

The Sabre boat I help build has four 15" diameter fans for venting the engine compartment. They are temperature controlled, if the temps get too high... the fans come on. They move a lot of air and are fairly noisy. There is about 8 sq ft of air inlet, I don't remember the size of the outlets. The boat is running with two 900 hp Volvo turbo diesels. Vague memory from talking with the designers is the temperature setpoint was determined based on Volvo specs.

There is a lot of money in that compartment, Why not run the engines in the right conditions? Sabre followed the Volvo Installation Manual.

The Sabre is a 66 ft boat, 3 berths/3heads starting at $3.5M, they do their best to do it right.

 

[BB marine]

This is a follow up on my Engine Compartment ventilation. We are cruising the Tennessee River and have had great weather, Actually very warm weather. The days are in the low 90's and water temperature 85F. The concerns I had running in warmer southern waters are as expected. After 2hours of running I start to see engine compartment temperatures as high as 158 F. I feel this is way to high, ABYC say its way to high. USCG which uses reverences to ABYC feel it is to high, and last but most important Volvo Punta feel it is to high. All agencies and manufacture state no higher then 30 F above ambient.

Cutwater representatives responded to my email about my high compartment temperatures. This is the response " I talked to Volvo. They said they would prefer the engines to be as cool as they can but didn’t give an exact temp rating. I specifically asked the question and it seems like a pretty loose guideline. I also asked about longevity and they said doubtful that the temperature where you are running will cause any problems. Our engine rooms on every boat built is at least what you are seeing. I have one with 2000 hours on it and it checks out like new. They rate the aluminum block diesels for 3000-4000 hours so looks like things will be just fine. "

Thank you,( I left out the signature )

Basically Fluid motion knows that this is the temperature of the compartments and actually states every boat that they have built is seeing at least what I am seeing in temperature. High engine temperatures are not only bad for the integrity of the power plant and efficiency, but electronics, fuel, wiring, hoses, can be compromised with temperatures close to 160 F. Part of a boat build is a proper engine compartment ventilation system. Fluid motion left this step out.

I will continue to pursue this and post follow ups. Many are not aware of this. Other then a slight change in performance the issue is hidden. When generators don't work correctly, relays fail, inverters fail, battery chargers fail, sensors fail, fuel gets to hot and causes hard starts, many just replace or pay for troubleshooting with no real answers. Maybe look a bit deeper in the environment that the power plant and components are running in. Sorry for the rant, we purchased a well designed boat at a well designed price. I question why they would omit a very important component (proper engine Ventilation )
These are pictures of the engine compartment temperatures, top number is compartment temperature , bottom number show ambient temperatures, I did see temperatures reach 158 F and climbing but started opening hatch then.


This is my resolution for this trip after 2 hours of running the temperatures climb to 155F to 158F I then open the hatch in the pilot house. This helps maintain the temperature to 127F to 130F which is on the high side but except-able. It is extremely loud in the pilothouse. I am also running my exhaust blower continuously. More ventilation is needed yet!

 

[Wildcats]

After reading this thread I was intrigued by the temperatures people were observing. I take it that they were monitoring temperatures near the air inlet (i.e. near the air filter). I wondered if the temperatures being measured were reflective of heat radiating from the engine or if the entire engine compartment was that warm. I decided to monitor our R31 engine compartment temperature about 2 feet behind the engine on the storage tray.

My wife, two guests and I boated from Cap Sante Marina in Anacortes Washington to the Port of Everett on Sunday, August 11th. The high temperature for the day was 77 degrees while the previous night's low was 61 degrees. We went through Deception Pass and in an effort to reach that location about an hour after max flood we motored for the first hour at 7 knots. After passing through Deception Pass we motored the rest of the time at about 14 knots. Total distance was 44 nautical miles. Total travel time was about 4 hours from dock to dock. We departed Anacortes at 10:36 AM and arrived in Everett at 2:16 PM.

I placed a Reed temperature and humidity data logger on the storage tray behind our D4 Volvo engine. Here is a graph of observed temperatures at that location for the trip. Our engine, once warm, ran at its usual 185 degrees for the entire trip. Click on the thumbnail to see a larger image.

Our starting temperature in the engine compartment was 64 degrees. The temperature was measured every 10 minutes. The maximum observed temperature was 69.4 degrees when we arrived in Everett. After docking in Everett, we found the maximum engine compartment temperature to be 81.7 degrees at 5:36 PM, or about three hours after engine stop.

I am curious as to where others measured their temperatures since we found in this "mini experiment" that temperatures in the engine compartment were much lower than what others observed. Is this because they were measuring much closer to the engine (i.e. near the air inlet) where radiant heat might affect the results? Andrew Custis, the General Manager for Ranger Tugs noted in previous postings that Ranger Tug has not seen a problem related to high engine compartment temperatures. If our measured temperatures are reflective of overall conditions in the engine compartment I am not concerned but I be would curious as to others take on things.

Tom

 

[BB marine]

Tom, your test showed remarkable low temperatures. I have a sender at the helm and in the engine compartment. My results are not as good as yours at the helm. On a clear day my pilot house temperatures usually are slightly above Ambient. During your test you noted the Ambient temperature was 77 degree F yet your engine compartment with a 185 F running engine stayed below ambient all day and only changed by 5 degree F after close to 50 mile run. I can only assume you found a cool spot in the compartment. How is all the radiating heat from the engine being removed from the compartment. The Rangers and Cutwater build have one way to get the heat removed. The engine. The only way for fresh air to enter the compartment is the air gaps around the aft section of the cockpit. When the engine is running there should be a slight depression in the compartment (Negative pressure) The air is pulled in from the gaps and used to supply air for combustion and to help cool the compartment. At High cruise speed your D4 is pulling in over 400CFM of air just to run run properly and needs this air to be cool for efficient combustion. The depression needs to be slight if it is elevated it will starve the engine for air. I believe the gaps in the cockpit ( Ranger/Cutwater ventilation system ) fulfill this but do not fulfill the compartment ventilation for proper cooling. Your results show they do but I question the location of your temperature sending unit.

(1) Aft of the engine air sampling is testing incoming air from the aft section of the boat (air being pulled in.
(2) Air sampling should be taken at a high point of the compartment ( heat rises)
(3) Air sampling should be taken in the area where the highest expected heat is to confirm you are protecting all electrical and mechanical components from the heat generated from the operating engine. You want to know the warmest point not the coolest point.
(4) Volvo recommends that air removal is at the high point,Volvo recommends that the air temperature be sampled at the air filter to measure the temperature of the air used for combustion and states this air should not be above 113 degrees F to provide proper efficiency of the running engine.
(5) Volvo also recommends that the warmest portion of the compartment not exceed 30 degrees F above ambient.

The warmest portion of the compartment will be found in the area furthest from where incoming air. In the case of the D3 installed in C26, R 25 and R27 this would be just in front of the air filter. This area in my C26 has seen temperatures above 160 F high enough to possibly damage electrical components (Max temp is 158F for electrical components). High enough to reduce the engine performance by 10% reducing my 220Hp to 200hp. (max temp is 113F to maintain rated performance)

The area just aft of the engine, high point air sampling found, air to be 15 degrees cooler because there is a large open area that has not been heat soaked from the 180 degree engine. ( my C26 testing)

I installed 450 CFM exhaust blowers one mounted aft of the engine, one mounted in front of the engine. I installed an extra 45 cubic inches of intake vents all bringing air in close to the air filter to help lower induction air. The opposite side of the compartment exhaust blowers. Intake vent hose routing low in compartment, exhaust blowers mounted high. This is a standard marine Diesel engine compartment ventilation system. With this system I have been able to maintain a engine compartment specification that is with in Volvo and ABYC specifications lowering the highest compartment temperature to 30 degrees above ambient at high cruise speed with both blowers running.

I like the test method you used but play around with the location find the warmest area. Hopefully with the large compartment that the R31 has you will be ok. The smaller unventilated Tugs and Cuts will be much higher I believe. Variables that come into play when measuring compartment temperatures are outside ambient air temperature, surface ambient water temperature, air monitoring at compartment high point, monitoring temperature of air exiting the compartment ( not coming in) Engine temperature, Time of running time. ( I find it takes about 2 hours of run time to heat soak the compartment to bring the compartment to its maximum temperature. In the past I have seen the compartment maintain 160 degrees F for 8 hours after a 100 mile run with ambient outside temperatures in the high 80's and water temperatures in the mid 80's. The humidity in the compartment at Zero, evaporating all the water from the bilge. My 3 drip a minute from the packing evaporating. The waste tank maintaining a temperature of 142 degrees F. ( IR gun used to monitor)

I highly encourage Ranger and Cutwater owners to do the same test as Tom. From what I have been told from Fluid Motion I'm the only owner that has experienced high compartment temperatures. The only reason I question this is I did receive the C26 Sea trial from NMMA representative, this sea trial was performed by Fluid motion and the results were the same temperatures at the air filter same reading I have recorded (60 degrees above ambient). I hope you all find Fluid Motion is correct, I am the only owner that has experienced the elevated temps.

 

[Cutwater28GG]

I have to think Brian that the engine compartment layout of the 31 vs the 26 (with the engine further inside the cabin on the 26) has quite a dramatic effect on engine heat retention.

 

[Wildcats]

Thanks Brian and Gavin for your input.

Brian, the ambient temperature on the day we traveled started out in the low 60s and the high for the day was 77 (data from NOAA weather). We traveled earlier in the day and the ambient temperature was never as the high for the day. Plus, we were traveling over an ocean with a temperature that averages 53 degrees F in August. The hull probably acts like a heat sink and cooling through our raw water inlet to the heat exchanger also helps.

I honestly never thought about the engine compartment temperature (I probably should have!) until I read your and others postings. You make a good point about the ventilation being reliant on the separation of the hull and cockpit liner as the apparent sole source of air circulation for the engine compartment. I didn't realize that the D4 consumes 400 CFM which if you think about it, is a significant amount of air needed for the engine.

You are right about the location, it could be a "cool spot" in the engine compartment. I don't know how the engine compartments are configured on the Cutwaters. We will be going to the Rendezvous in Roche Harbor so that will be an opportune time to re-run the experiment with the temperature and humidity logger in a different location. I do wonder about radiant heat from the engine biasing the results if the logger is right next to the engine, but having it higher in the compartment will be something easily done. I will post the findings when I have them.

 

[BB marine]

I agree with Gavin your results will be much different from mine because of the engine location in the boat. I still belief that that regardless of compartment size or engine location a true compartment ventilation system should be used especially with a diesel powered boat with open bulkheads between engine compartment to living space.

I believe the results of even a C26 in the PNW will have compartment temperatures that are lower then what would be experienced in the midwest or southern states. You were right on in your statement 53 degree ocean water is helping to heat seek the compartment temperatures along with air ambient temperatures lower. The C26 Fluid Motion/Volvo sea trial proved that. The differential in ambient was out of specification ( sea-trial conditions - 55 degree F ambient air and 51 degree ambient sea water temperature resulting in air temperature at engine air inlet of 116 degrees F, air temperature in the front of the engine 116 degrees F and top of the engine 116 degrees F). The temperatures that were recorded were reasonable for those conditions but still 61 degrees F above ambient. The same boat running in 80 degree F water and 85 degree F ambient air is now going to see compartment temperatures of 145 degrees F or higher. In my case 150 degrees F to 160 degrees F. before adding additional ventilation.

I look forward to seeing your results. I do expect your results to be better then what I have experienced . The R31 compartment and engine location is in a much larger opening. The photo below will show what Gavin was talking about. The C26 engine installation is located more in the pilothouse under the deck. There is a deck hatch in the pilothouse for oil and belt inspection and a step needs to be removed in the 1/4 berth to work on the engine.