40 sedan bridge forum

[Islandbound]

I have searched forum and Internet for various data points in rpm vs speed still not seeing many and with any consistency. I acquired my '98 400 DB with cat 3116s six months ago and am a full time liveaboard. I have gotten out many times now and have yet to see 20kts cruise speed in gps. Recently 1/4 tanks and half water I was able to cruise about 18kts @ 2600. Just filled it to the gills with fuel and water and basically digging big hole and not getting on plane. WOT = 2800-2850. Those with same engine configuration let me know your thoughts. I am still hunting for documentation on correct prop size / pitch to verify, any insight on this is appreciated too. Regards,


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[ZZ13]

I have searched forum and Internet for various data points in rpm vs speed still not seeing many and with any consistency. I acquired my '98 400 DB with cat 3116s six months ago and am a full time liveaboard. I have gotten out many times now and have yet to see 20kts cruise speed in gps. Recently 1/4 tanks and half water I was able to cruise about 18kts @ 2600. Just filled it to the gills with fuel and water and basically digging big hole and not getting on plane. WOT = 2800-2850. Those with same engine configuration let me know your thoughts. I am still hunting for documentation on correct prop size / pitch to verify, any insight on this is appreciated too. Regards,


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It depends on which Cats you have. Sea Ray had both the 300HP and the 350hp version available for your year. If you have the 300HP version, based on a sea trial I did of the same configuration your numbers look about right. WOT should be 2800rpm so you are good there. Fully loaded (especially with water, which is a huge weight right in the very stern of the boat) did you try using the trim tabs to help you get on plane? I know several here have the 350hp Cats (such as CWIERT, who has the same year boat as you) and maybe one of them will post on their performance experiences.

 

[mjmason1]

I have searched forum and Internet for various data points in rpm vs speed still not seeing many and with any consistency. I acquired my '98 400 DB with cat 3116s six months ago and am a full time liveaboard. I have gotten out many times now and have yet to see 20kts cruise speed in gps. Recently 1/4 tanks and half water I was able to cruise about 18kts @ 2600. Just filled it to the gills with fuel and water and basically digging big hole and not getting on plane. WOT = 2800-2850. Those with same engine configuration let me know your thoughts. I am still hunting for documentation on correct prop size / pitch to verify, any insight on this is appreciated too. Regards,

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I am going to assume you have the 300hp Cats. I have the 350hp Cats. At 2400 rpms I am doing 18-20 kts. Last year while going to Block island I was going 26 kts at 2750 rpms. The conditions were perfect. I know the books say my Cats should top out at 2800 rpms. I never seem to get that. You also might want to check your Racors.

 

[cwiert]

I have searched forum and Internet for various data points in rpm vs speed still not seeing many and with any consistency. I acquired my '98 400 DB with cat 3116s six months ago and am a full time liveaboard. I have gotten out many times now and have yet to see 20kts cruise speed in gps. Recently 1/4 tanks and half water I was able to cruise about 18kts @ 2600. Just filled it to the gills with fuel and water and basically digging big hole and not getting on plane. WOT = 2800-2850. Those with same engine configuration let me know your thoughts. I am still hunting for documentation on correct prop size / pitch to verify, any insight on this is appreciated too. Regards,


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Yes, I have the same year boat, with the 350HP 3116 CATs. (Sea Ray calls them 350HP, but I think they're really 340HP). My props are 22x24 (stock, I believe).

I just took it out last week for a test run. Clean bottom, clean props, 1/2 tanks of fuel, and 1/4 tank of water. My WOT was exactly 2800. At that RPM, I was doing 30 mph or 26 knots.

If memory servs me correct, I was at cruise at about 2300-2400 RPM and on plane...right around 20 knots (maybe a tick less).

I'm curious to see what engines you have. I think the boat would struggle with the 300 HP 3116s (which I think is really 290 HP)...especially with full fuel/water and any growth on the bottom.

Hope this helps.

 

[cwiert]

While we're on the topic of WOT, I've been told by my dockmates, that with diesels, 10% of each trip should be at WOT to keep the engines clean. True or Myth?

 

[mquiet]

I don't run mine WOT 10%, but I will make sure I can reach WOT every few months.


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[PMC]

I don't run mine WOT 10%, but I will make sure I can reach WOT every few months.


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Same here. Most of my running is at cruise speed, and I run WOT only for diagnosis tests (rpm, speed and temp, etc.).

 

[fwebster]

While we're on the topic of WOT, I've been told by my dockmates, that with diesels, 10% of each trip should be at WOT to keep the engines clean. True or Myth?

My opinion is that 90% of what you hear on the dock is wrong and 99% of it doesn't pertain to your engines, transmissions boat or circumstances. Verify all the "dock talk" you hear before implementing it.


The best source of information like this is your engine manufacturer's maintenance and operation manual. Caterpillar says that for E Rated engines, you should not run at WOT more than 8% of the time. This is from a Cat publication on engine ratings:


"E Rating (High Performance)"

"For vessels operating at rated load* and rated speed** up to 8% of the time, or 1/2 hour out of 6, (up to 30% load factor). Typical applications could include but are not limited to vessels such as pleasure craft, harbor patrol boats, harbor master boats, some fishing or patrol boats. Typical operation ranges from 250 to 1000 hours per year.

I don't run my engines that hard. Maybe once or twice a year, I'll push the throttles to see what WOT is, but I see very little or no advantage to running these engines past a normal comfortable cruise speed which is 2300 for me. The fuel burn is 25% lower, the engine noise is lower and the ride is better. Running 3 kts faster just might get us there a little faster, but it also means we miss part of the most enjoyable part of boating.....i.e., running the boat and the trip to our destination.


* rated load in your case means your boat is propped to turn 2800-2850 RPM at WOT.
** Rated RPM is 2800 for E rated 3116's.

 

[cwiert]

Thanks Frank. I was hoping you'd see my post and chime in. I appreciate the response.

 

[mjmason1]

We finished the salon flooring. It came out pretty good. We took the carpet kickplates and made padded vinyl ones.
For some reason all my pictures come out side ways. Sorry!

 

[ZZ13]

Looks great Mike! Really good craftsmanship. Now you gotta keep it. Ha!

It looks like you moved the Crusair temp sensor from the unit to outside on the dinette sidewall. How is that working out?

 

[mjmason1]

Looks great Mike! Really good craftsmanship. Now you gotta keep it. Ha!

It looks like you moved the Crusair temp sensor from the unit to outside on the dinette sidewall. How is that working out?

We moved both temp probes out into the open. We seem to have truer temps. We had a hard time regulating the temps until we moved them.

 

[Islandbound]

I have searched forum and Internet for various data points in rpm vs speed still not seeing many and with any consistency. I acquired my '98 400 DB with cat 3116s six months ago and am a full time liveaboard. I have gotten out many times now and have yet to see 20kts cruise speed on gps. Recently 1/4 tanks and half water I was able to cruise about 18kts @ 2600. Just filled it to the gills with fuel and water and basically digging big hole and not getting on plane. WOT = 2800-2850. Those with same engine configuration let me know your thoughts. I am still hunting for documentation on correct prop size / pitch to verify, any insight on this is appreciated too. Regards,


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Update - reviewed my engine surveys they were marked 350hp, I called Ring Power Cat they confirmed via serial number that engines were shipped from factory as 350 hp.

I have no run-ability issues with the motors. Quite the contrary. They continue to start flawlessly, run smoke free and vibration free, come up to rpm and maintain temps as indicated during survey by cat mechanic.

Don't want to jump off deep end, but it just seems like not pushing enough water, "under propped"...? Next bottom cleaning or haul out will investigate / confirm prop and pitch.

Still welcome the feedback.

 

[NaughtyDog]

Has anyone changed or been able to service their holding tank sensors on their 400DB? I understand you have to access the top of the tank. Is this possible with the port exhaust 'tubes' in place? Would this be a in water or out of water job?


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[ROB BONDY]

Tying to fix my port fuel gauge that is not working. I grounded out the gauge and it pinned so the gauge must be fine. Should i be checking the sending unit from the tank?? How do i access it??

 

[ZZ13]

Tying to fix my port fuel gauge that is not working. I grounded out the gauge and it pinned so the gauge must be fine. Should i be checking the sending unit from the tank?? How do i access it??

Not sure this is the right answer. But, lower your salon sofa. Open the compartment. You will see a round cover plate over the fuel tank area. Take that plate off and see if it is by chance access to the sender. I have never removed that plate so I don't know if it is. Worth a try.

 

[truk911]

I need a new flag pole and want to know where to mount it. When I bought my 2001 400DB, the PO never mounted a flag pole on the transom. I used a teak flag pole that I had from my previous boat, putting it into the rod holder. That work great until we were coming home from a trip last season in 3-5 footers and we lost the flag pole to the Sea Gods.

The question I have is what size flag pole is appropriate for this size boat and where should it be mounted? Any help, or pictures, are welcomed and appreciated.

Thanks!

 

[cwiert]

I need a new flag pole and want to know where to mount it. When I bought my 2001 400DB, the PO never mounted a flag pole on the transom. I used a teak flag pole that I had from my previous boat, putting it into the rod holder. That work great until we were coming home from a trip last season in 3-5 footers and we lost the flag pole to the Sea Gods.

The question I have is what size flag pole is appropriate for this size boat and where should it be mounted? Any help, or pictures, are welcomed and appreciated.

Thanks!

I keep mine exactly where you used to keep yours. I have a teak pole which I put in the port rod holder. I'll be sure to remove it when I'm underway after hearing your story.

 

[The crime scene]

I have a new ice maker coming that will fit on the rear deck where my freezer (non ice maker) used to be. The freezer finally gave it up. I think the install is going to be relatively simple and I will only have to find a pressure line to tap into for a water supply. Anybody have any suggestions of where I should tap the water line? Does anybody have an ice maker back there and if you do.....where is it tapped? Any help is appreciated.

Keith

 

[h_gerry]

I keep mine exactly where you used to keep yours. I have a teak pole which I put in the port rod holder. I'll be sure to remove it when I'm underway after hearing your story.

I have my flag pole in the rod holder as well. So that the pole does not turn, I knocked the teak pole so that it fits around the bolt that goes across the bottom of the rod holder. I also attached at small bungee cord to the rod holder and put a screw eye into the teak pole. Now I can secure the pole into the rod holder so it won't fly out.