410 Performance problem

Since the engines turn up rated RPM unloaded, then your issue is loading of the engines.

Either the props still have too much pitch, the bottom is fouled creating drag, the weight on the boat is too much, or the boat is out of trim. It sounds like you have eliminated all but the props. Most prop shops will work with you to tweak the wheels for a boat. Before doing anything else, I'd probably talk to your prop guy. For 100 rpm and a knot of speed, you aren't looking for much......likely all he'll recommend is removing a little of the cup in the props.

Good luck with it.........
 
fwebster said:
Since the engines turn up rated RPM unloaded, then your issue is loading of the engines.
Click to expand...

So you're saying that if the engines can turn max recommended rpm not under load it isn't fuel restriction? A diesel engine burns the same amt of fuel at a given rpm whether under load or not? Do I understand that correctly?
 
No, I'm only saying that because the engines turn up the unloaded WOT rpm that it should be able to do it under load. Therefore, there is no mechanical reason the engines won't deliver 2800 rpm under load.

The reason I don't think it is a fuel restriction is because it never gets to WOT under load....it peaks at 26-2700. If there were a fuel restriction, the fuel cavity in the head and the secondary filters hold enough fuel for the engines to run up to 2800, then they would slow to whatever the filters will let pass. Even then, the rpm will fluctuate some. But it seems that the engines are producing but are being limited by the props or a fouled bottom, which the owner says is clean. All this is second guessing basaed on the owners description of the problems.
 
The props that were on it were 22X23 and I was having this problem not only with the RPM but the speed also. Everyone that I have spoke with or read on this site that have the same boat are topping out at 25-26 knots where all I was able to get was 21 knots. I had the props removed and tuned and repitched to 21.75X21.75 and now gained a slight RPM gain but still no speed. I am thinking of having the boat hauled to inspect the bottom which my diver says is good but in the marina we are in visibility is terrible.
 
I may be mistaken but the added rpm does not necessarily mean you will gain any speed.
You have less wheel now.
 
On another note I had a water leak in the weld of my water heater. My wife was at the boat for a week and didn't know that anything was leaking. When I got to the boat there was a short alarm on the Sea Ray Monitor system but I didn't get to it in time to see what it was. I started looking in the engine compartment and heard the noise of the leak. I then pulled back the carpet runners and and checked my dry storage areas and there is a bilge pump by the collecting pans for the shower and A/C condensing lines. It had water in it. Upon further investigating I found a small patch in the center compartment which I am guessing is where they filled the underneath with foam. Water was coming out of this so I removed the patch and wet vac about 12 gallons of water from the foam under the compartment. It is dry now because I have kept the water off and am waiting on Sea Ray to replace the water heater, which they say they have to make?. My question aren't these compartments all sealed and how could the water heater leak get this area wet if they are sealed?
 
You may have added a whole new dimension to this.
Waterlogged foam is a real problem- it's supposed to be closed-cell and unable to absorb water, but that doesn't seem to be the case in the real world. It can and does happen, and fuel tanks and stringers rot out from it. But the water would have had to have been there before the water heater leak if it does turn out to be part of your problem- you've had the performance problem from day one.
Don't know enough about the particulars of your hull, but mine sounds similar with foam filled voids under the compartment, which in my boat runs continuously from the rear bulkhead all the way to the forward stateroom.
I will say this much- the water you got out weighs 100 lbs.. Add several hundred gallons soaked into waterlogged foam and you've got the reason for the poor performance. Not trying to sound the alarm and this may not be your problem- but it may be more than a coincidence and certainly warrants further investigation.

I believe Frank W might have some insight into this- perhaps you need to drill some additional exploratory holes to see the extent of the water intrusion.
 
I don't see how a leaking HWH can make any water in the dry storage areas. The HWH on the 410DA is in the ER. Even if you opened up the drain on the HWH the water would fill into the bilge....actually the forward bilge, and be pumped overboard by the bilge pump.

Most likely your sumps are not workiing and are overflowing everytime you take a shower into the dry storage area. I've had to replace both of my sump switches and one of them twice.
 
Here's how Dominic:

The water leaks into the bilge and ends up in the bilge sump. The sump is formed by 2 X 4's cut, fit and glassed into the hull then the bulkheads are installed to form the front and rear sump walls. Any place between the water heater and the sump can have a void in the fiberglass. If the void opens to the bilge area, water can enter and it will work its way to the hull. There can also be voild in the glass work in any of the bilge sumps. Once near the hull it can run forward to the foamed area under the cabin floor. Over time, water will fill the area under the floor and sometimes the only way you know it is when it leaks out of the screw holes in the storage compartments.

Trust me, I know it can happen (I found out the hard way on a 390EC) and that it is also almost impossible to diagnose and is even harder to fix where it won't happen again.

But based on the entriety of this thread, I tend to think your last sentence is the correct answer.
 
Frank-
I've always wondered about the underlying structure forming the flat bottom of the hull's interior. Is this just 2x4 cross framing tabbed into the hull bottom and overlaid with plywood?
I have no reason to suspect a problem, but having a huge void like that in the bottom of the hull that I can't inspect bothers me...
I was thinking about cutting an inspection hole or two, then using a waterproof inspection port to close up the hole(s). Would you recommend doing this, or is this usually not a concern?
 
I had the problem I described above with my '88 390EC.

I eventually found a small void in the fiberglass covering the V in the bottom of the forward engine room sump. By the time the water under the floor became apparent, it had run both directions from the forward sump and was most evident in the storage compartment under the cabin floor about 3 ft forward of the front of the water tank, which was the lowest part of hull when the boat was in the water. I had to cut inspection ports....read "hole saw" in the flat part of the engine room floor just before and aft of the generator mounting location, and in several spots under the cabin floor. I chose to use water tight inspection ports in the places I sawed holes so that I could check the floor and vacuum out any water that turned up in the future. You make your own call on this one, but if you use inspection ports, don't cheap out......get the best ones you can find because you do wat them water and air tight. Aside from the obvious reasons of keeping the area dry when you wash the engine room, that closed cell foam eventually soaks up water and is very slow to give it up once its there. The result is that it begins to smell awful before you even begin to get it dry. I vacuumed 2 years, every time I went to the boat, before the foam began to dry out.......the smell never did go away, so it is imperative that you have good inspection ports so you can keep it captured below the floor.

I should also add that the 2 X 4's that make up the bottom part of the bilge sumps in the 390 are not tabbed to the hull.......they are "buttered" with resin placed into position then the fiberglass is applied to form a water tight (or so they thought!) sump.
 
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You betcha..........to the dealer, who then sold it to the buyer we already had. A 3-way deal is hard to do but we were able to make it work to get the sales tax savings on a trade.

I am in regular contact with the new owner who still owns and loves the boat after 11 years.
 
Update on my props....

As I stated in an earlier post, fully loaded, I'm turning just under 2800 RPMs. Yesterday, I dropped off my extra set of props at the prop shop. I spent considerable time going over my numbers and plugging them into the computer at the prop shop and discussing my issues and concerns.

Here's some history:

The 410DA-D came from the factory with 22 X 23 4 blade nibral hytorq with a L-cup. I'm not really sure what the L is, except for lite...but that's all the quantitative info I have.

When I purchased the boat, the previous owner (Sea Gull) had the props retuned, as per an MRI scan, to 22.25 (average) with a #4 cup -.063. At the survey, with these props, I was able to turn just a hair over 2800 RPMs BUT....and this is a big BUT....I was not fully loaded....~ 1/4 fuel, no water, no gear, 4 POB and clean bottom.

I purchased a set of spare 4 Blade nibral Hytorq props and had them Prop Scanned (different than MRI scan) to 22 X 22 with a #4 cup. The motors turned right up to 2800, but again, I wasn't FULLY loaded...I had all my 'stuff' on board but just 1 POB and ~ 1/2 fuel and a clean bottom.

This past Sunday, with FULL LOAD...FULL Fuel, Full Water, all my 'stuff' and 4 POB and a mostly clean bottom I turned 2767 RPM....

RPMs were measured with a pair of previously calibrated Aetna digital tachs.

As per the prop shops computer and some converstion with the techs, I will have the props re-worked to 22 X 21.5 with a # 5 cupping. The cuppling will be a full cupping. In other words, the cup will come all the way around the 'tips' of the blades. Most cupping, from what I'm told, does not include the tips. The props that were on the boat were not cupped at the tips.

I am expecting the motors to turn 2825-2850 RPMs Fully loaded. The full #5 cupping is expected to ehlp maintain my cruise speed of 21-23 Knots. I expect to cruise at 2400 RPMs.

Lesson learned....ONLY test for max RPMs FULLY loaded.
 
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So, you are going to repitch your wheels for 33 rpm.....roughly 1%? And, what happens when you burn off fuel or use some water?

Me thinks your pencil it too sharp on this one.............
 
Frank:

I'm shooting for 2825-2850 RPMs (Plus 58-83 RPMs, ~ 2-3%).

I suspect that as I burn off fuel or use some water, I'll still run at 2400 RPMs, I'll just go a little faster and burn a little less fuel.

I had the props that are on the boat Prop-Scanned as a matter of proper practice and to baseline my performance before installing them. I'm having my second set of props Prop-Scanned for both proper practice and some final tweaking to add some margin.
 
So, is your boat operating normally? Does it seem heavy (water saturation)? Was it the props all along?
 
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