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FOUND! Roamer 46

 
 
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Old 12-06-2007, 09:29 AM   #16 (permalink)
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Why 10 knots

Chris, You sold yourself short on the DD argument. They shouldn't be the same price as the teeny weeny yanmars. Rebuilt DD's could be a 50% savings over new tenny weeny anythings. THAT's where your arguement gains some real weight (get it - DD's = weight - lol).

OK, we have to do a little math here; this could get interesting. Why pick 10 knots? If you're buying mini-power, why not hull-speed? Could it be when a person decides to buy 'low power', it is not primarily for cost reasons? I'm from that in-between world of trawlers - not willing to depend on the wind like a snailboat (hey, I like that term), but willing to lope along at hull-speed.

How about some fun with numbers. A little 'rule of thumb' math says hull speed is between 1.2 and 1.34 times the square root of a vessel's waterline length. In the case of the 46 in question that turns out to be 7.7 to 8.2 knots. As you pointed out before, and I agree, these wide body Roamers are not the 'best displacement design', so lets take the less efficent figure 7.7 kts. The shaft power needed to push this boat to hull speed is about 5 HP per ton, and we'll figure the 46's loaded weight is around 20 tons (guestimate). This is using the low end of efficiency, but still comes out to only 100 SHP. Figure for 3-5% loss in drivetrain, 108 crankshaft hp is needed to reach hull speed (18% of 600HP - tw300's). Now to get to your selected 10 knots. Another 'rule of thumb' I've read is double the HP for every 2 knots of additional speed (until the boat 'planes). So 216 HP (total) gets 10 knots. Still a bit short of the 300.

In a few years I'll have my boat in Florida and you can blast past me. I'll accept that. I will smile and wave, because you are a boater and you use your boat (of course I wave at the 'dockers' too, but my smile says something else).

Hey, I'm coming to Stuart, FL in January for Trawlerfest. You wanna see how the other half lives? If we can get together, it could be a very interesting 'cocktail hour'.
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Old 12-07-2007, 04:07 PM   #17 (permalink)
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OK, the 200hp Nanni Toyota diesel quote came in at $30k even. 330hp units add $10k. 8v53s needing a cylinder kit on one jug are $5k w/gears, and properly propped for the speed I always run at (8-9kts + a few for when you really want to fly lol) they might actually be fairly efficient.

The idea that low speed = underloading is mistaken. Tie a big wheel onto those shafts or bump up the pitch and you can perfectly load (or overload) at any rpm. There's an excellent discussion on this topic on the Hatteras forum at sam's marine that's based on real-world repropping and derating of a 61 Hattie w/12v71TIs. The results are impressive.

boatdiesel.com's calculators say that a slow planing hull weighing 40,000lbs and having a 42 foot waterline needs the following to Achieve a Cruising Speed of 10 kts:

Required Power
Total At Props: 178 SAE hp
Total At Flywheels: 183 SAE hp
At Flywheel per Engine: 91.7 SAE hp

Sounds like Lehman's wouldn't provide enough wiggle room. Cats might. DD's would, but they'd be noisy and dirty. And cheap. It looks like 325hp per side would yield a max speed of 19kts @ 40,000 pounds.
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Old 12-11-2007, 06:55 PM   #18 (permalink)
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Quote:
Originally Posted by q240z
OK, the 200hp Nanni Toyota diesel quote came in at $30k even. 330hp units add $10k. 8v53s needing a cylinder kit on one jug are $5k w/gears, and properly propped for the speed I always run at (8-9kts + a few for when you really want to fly lol) they might actually be fairly efficient.

The idea that low speed = underloading is mistaken. Tie a big wheel onto those shafts or bump up the pitch and you can perfectly load (or overload) at any rpm. There's an excellent discussion on this topic on the Hatteras forum at sam's marine that's based on real-world repropping and derating of a 61 Hattie w/12v71TIs. The results are impressive.

boatdiesel.com's calculators say that a slow planing hull weighing 40,000lbs and having a 42 foot waterline needs the following to Achieve a Cruising Speed of 10 kts:

Required Power
Total At Props: 178 SAE hp
Total At Flywheels: 183 SAE hp
At Flywheel per Engine: 91.7 SAE hp

Sounds like Lehman's wouldn't provide enough wiggle room. Cats might. DD's would, but they'd be noisy and dirty. And cheap. It looks like 325hp per side would yield a max speed of 19kts @ 40,000 pounds.
That calculator ain't all it's cracked up to be.

I water-tested a 48' roamer down here in FL 2 or 3 years ago with 330hp cats and it turned 21kts on GPS.

When it comes to powering a boat, go Tool-Time on it. You don't have to use the power if you don't feel like it, but then you'll have it when you need it.

From the options you listed, I would go with the detroits and be done with it. So what if they're smoky...you can buy one hell of a scrub brush with the $25k you are saving. Lol.
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Old 12-11-2007, 06:58 PM   #19 (permalink)
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Quote:
Originally Posted by artwork
Chris, You sold yourself short on the DD argument. They shouldn't be the same price as the teeny weeny yanmars. Rebuilt DD's could be a 50% savings over new tenny weeny anythings. THAT's where your arguement gains some real weight (get it - DD's = weight - lol).

OK, we have to do a little math here; this could get interesting. Why pick 10 knots? If you're buying mini-power, why not hull-speed? Could it be when a person decides to buy 'low power', it is not primarily for cost reasons? I'm from that in-between world of trawlers - not willing to depend on the wind like a snailboat (hey, I like that term), but willing to lope along at hull-speed.

How about some fun with numbers. A little 'rule of thumb' math says hull speed is between 1.2 and 1.34 times the square root of a vessel's waterline length. In the case of the 46 in question that turns out to be 7.7 to 8.2 knots. As you pointed out before, and I agree, these wide body Roamers are not the 'best displacement design', so lets take the less efficent figure 7.7 kts. The shaft power needed to push this boat to hull speed is about 5 HP per ton, and we'll figure the 46's loaded weight is around 20 tons (guestimate). This is using the low end of efficiency, but still comes out to only 100 SHP. Figure for 3-5% loss in drivetrain, 108 crankshaft hp is needed to reach hull speed (18% of 600HP - tw300's). Now to get to your selected 10 knots. Another 'rule of thumb' I've read is double the HP for every 2 knots of additional speed (until the boat 'planes). So 216 HP (total) gets 10 knots. Still a bit short of the 300.

In a few years I'll have my boat in Florida and you can blast past me. I'll accept that. I will smile and wave, because you are a boater and you use your boat (of course I wave at the 'dockers' too, but my smile says something else).

Hey, I'm coming to Stuart, FL in January for Trawlerfest. You wanna see how the other half lives? If we can get together, it could be a very interesting 'cocktail hour'.
Hey Artwork, just saw your post. Keep me posted if you're going to be around the area in January. I will show you my redone 427s....enough to curdle any trawler-owner's blood. Hehehe (just kidding).

As to hull speed, you have a point, it's a lot more efficient. I just can't get used to going that slow. Maybe I'll have to start. The gas dock just hit $3.65/gal, and I get less than 1mpg.
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Old 12-11-2007, 11:14 PM   #20 (permalink)
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A new twist in the calculus...ultra-low sulphur diesel. Old and cheap Lehmans, DDs, Cummins...they'll drop valves eventually because of it. New diesels will run just fine.

How does that impact the "repower with old and cheap technology that nobody else seems to want" argument? Additives by the barrel-full???
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Old 12-12-2007, 01:11 PM   #21 (permalink)
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Quote:
Originally Posted by q240z
A new twist in the calculus...ultra-low sulphur diesel. Old and cheap Lehmans, DDs, Cummins...they'll drop valves eventually because of it. New diesels will run just fine.

How does that impact the "repower with old and cheap technology that nobody else seems to want" argument? Additives by the barrel-full???
You've kinda got it backwards. It's a forward compatibility problem, not a reverse one.

By govt. mandate, diesels built after January 2007 are designed specifically to run on LSD or ULSD. Most diesel fuel sold in the US has already been LSD for awhile, which is Sulfur<500ppm. ULSD is Sulfur<15ppm or less.

Anyway, newer diesels (post '07) are required to carry pollution control equipment and are required to have different valve and fuel rail designs, to lower their emissions. In these engines, running anything but LSD or ULSD will cause damage.

However, you can certainly run a pre-ULSD mandate diesel on LSD or ULSD with no problems. Just make sure you change your fuel filters when you switch over, since ULSD has detergents in it and any leftover deposits from the old fuel will start coming loose.

So in a nutshell: Old fuel will damage the new engines, but new fuel won't damage the old engines.
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Old 12-14-2007, 11:34 AM   #22 (permalink)
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Well, somebody needs to go tell that to the good people at boatdiesel.com, because there are plenty of threads over there about ULSD not providing the lubricity the older engines require. Kinda like back in the day when they switched from leaded gas to unleaded and there were concerns about the old engines burning up their valve guides. Then again, I don't know if that turned out to be just an old wives's tale or not...

**** the internet. There's too much information! lol
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Old 12-14-2007, 11:35 AM   #23 (permalink)
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It turns out that d_a_m_n is a bad word here. lol
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Old 12-14-2007, 05:03 PM   #24 (permalink)
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Quote:
Originally Posted by q240z
Well, somebody needs to go tell that to the good people at boatdiesel.com, because there are plenty of threads over there about ULSD not providing the lubricity the older engines require. Kinda like back in the day when they switched from leaded gas to unleaded and there were concerns about the old engines burning up their valve guides. Then again, I don't know if that turned out to be just an old wives's tale or not...

**** the internet. There's too much information! lol
I have seen people on the internet ranting and raving about it for awhile, and can say with absolute certainty that it is a steaming load of BS.

The new fuel only represents a chemical difference of Sulfur<500ppm to Sulfur<15ppm. The original concentration of less than 500ppm was already so small that it is logically impossible that it could have had any significant lubricating properties at all at those levels, and even more impossible that the S<500ppm to S<15ppm change could have some mysterious engine-killing effect.

Are you aware of how small an amount you are talking about with ppm calculations? A part-per-million is equal to less than one single drop of water out of a pool of 50 litres. So think of having something like twenty-five 2-litre bottles of Coke lined up, and then open just one of them and take out just a single drop of liquid, and that's a good illustration of the scale of the quantities we are dealing with here.

It is a stretch to think that these amounts of ANYTHING, let alone sulfur, could have any lubricating effect on hundreds of pounds of moving iron. Even if that was a concern, diesel has lubricants added to it by the manufacturers anyway.

The problems people are having don't relate at all to the sulfur content. Rather, the new fuel is mandated to contain detergents, very much like gasoline. So, what happens is that switching fuel to the new composition provides a shock to the engine because the new blend with detergents built-in starts knocking all the years of built-up crud loose. Those deposits can then cause issues that need to be addressed, usually with the fuel system and valves.

But that's all that is happening....the fuel itself is not damaging the engines.
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Old 12-14-2007, 05:14 PM   #25 (permalink)
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Quote:
Originally Posted by q240z
Well, somebody needs to go tell that to the good people at boatdiesel.com, because there are plenty of threads over there about ULSD not providing the lubricity the older engines require. Kinda like back in the day when they switched from leaded gas to unleaded and there were concerns about the old engines burning up their valve guides. Then again, I don't know if that turned out to be just an old wives's tale or not...

**** the internet. There's too much information! lol
And you are right about the switch to unleaded gas from leaded. That would burn up the valve seats, because engines designed for leaded fuel came with soft valve seats and this setup didn't work so well with unleaded. Even then, correcting the issue was a simple $200 fix for replacing the valve seats with modern ones the next time you needed a valve job.

However, that isn't an issue here, because sulphur has NOWHERE NEAR the lubricating properties of lead. Lead has some of the best lubricating properties of any element, and so played a much larger role in gasoline than sulphur ever did in diesel. In addition, lead was added to gasoline in much larger quantities than sulphur was ever found in diesel.

It's apples and oranges.
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Old 12-14-2007, 08:15 PM   #26 (permalink)
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I appreciate your opinion and it's certainly consistent with EPA-endorsed clean-diesel.org, which says nobody needs to worry. Then again, EPA also endorses E10, E15, and E20 gasoline, though I have read enough sob stories from gas boat owners who had to rip out their fuel tanks this year to know that YMMV.

If the experts at clean-diesel are only willing to say that " ULSD fuel is expected to perform as well as" earlier fuels (underline added), it means they really don't know for sure. In any case, I'm not quite prepared to dismiss the folks on boatdiesel who report suddenly having to replace and repair engines with dropped valve heads.

Time will tell...
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Old 12-15-2007, 11:02 AM   #27 (permalink)
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Originally Posted by q240z
I appreciate your opinion and it's certainly consistent with EPA-endorsed clean-diesel.org, which says nobody needs to worry. Then again, EPA also endorses E10, E15, and E20 gasoline, though I have read enough sob stories from gas boat owners who had to rip out their fuel tanks this year to know that YMMV.

If the experts at clean-diesel are only willing to say that " ULSD fuel is expected to perform as well as" earlier fuels (underline added), it means they really don't know for sure. In any case, I'm not quite prepared to dismiss the folks on boatdiesel who report suddenly having to replace and repair engines with dropped valve heads.

Time will tell...
Ya, the Ethanol thing has been a complete friggin' disaster. The govt. screwed up big time on that one.

They designed the fuel based on automotive needs. It is ok there, because cars all have metal fuel tanks. They then mandated it for use at marinas, but totally failed to consider the fact that tons of boats have fiberglass fuel tanks, and that ethanol is a solvent that breaks down the epoxies used to hold the tanks together.

A real "doh" moment there.

I really think that ULSD is a totally different story, though. I would bet that everyone having problems could probably tie it back to gunk deposits in one way or the other.
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Old 12-25-2007, 06:51 AM   #28 (permalink)
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Christmas Day 2007

The missus and I are deep into an 11-day working vacation in which the mission is to 1) get all of the cr4p off the boat, b) crane out the SeaMaster 534TTi engines (534ci Ford industrial engines with two turbos and intercooling), gas genset (Kohler 10kw), original refrigerator, and R12 AC unit, and 3) shrinkwrap this beast before winter gets serious.

Getting rid of the AC ducting does wonders for improving mobility in the ER.



The port engine is now held in place only by gravity.




See those two pumps right next to the muffler? Well, when I started this project, you couldn't see any of the three because of all the AC ducting. There's a ton of space in there now. The plywood under both battery banks was rotten and will come out when I do the engine room. The R12 AC air handler is rotten through. How many times I gotta tell ya: galvanized does NOT belong in an engine room.



The salon headliner is down. The hatch is ready to fly out after I remove the 50 carraige bolts holding it in.



Old mattresses suck. So does the stuck steering shaft. Project for another day.



109th reason to not sleep around: You might get your a$$ stung.



OK, the aft deck was clean last week. Now it's full of junk again. OK, well, not all junk. Check out the solid mahogany drawers that somebody painted white over. You know...to brighten things up.



This was the first attempt to degunk the helm station. The wheel is off for better access to the gears when I get around to it. I'm gonna have a huge sack of bits to be rechromed. A cordless drill on the engine-end of the cables tell me that the tachs work!



For variety's sake, the missus decided to work at stripping the helm station. This will take time. Back to the engine room tomorrow.

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Old 12-25-2007, 07:07 AM   #29 (permalink)
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For comparison's sake, here's what it looked like in as-found condition:















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Old 12-25-2007, 01:13 PM   #30 (permalink)
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She looks better already! As I predicted in a previous posting, a cleaning and de-junking would make a world of difference. Looks like you have a great start on her. Carry on!
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