Very modestly powered Diesel Duck on YachtWorld...

[engine room]

Boat referenced in link:
https://www.yachtworld.com/yacht/1999-diesel-duck-trawler-9785299/


This "41" Foot Aluminum DD is powered by a 60hp Beta Engine. The vast majority of the DD boats I've browsed are powered by 120+hp engines. Any comments on how this boat must perform with such modest power? Are the majority of these boats overpowered? I've browsed several Seahorse boats with 140hp John Deere engines.

 

[North Baltic sea]

Good question.

If there is only a current or you are just pushing against the waves, I think the boat is underpowered to move properly at close to hull speed at sea.

I think that 100-120 hp would be more suitable, as it would leave a little margin and there would be no need to overload an underpowered diesel engine.

In sheltered waters in good weather, there is certainly no problem. So it depends on your ideas about where and how you sail.

 

[mvweebles]

Its a 1999, launched in 2005, and repowered in 2018 with 810 engine hours. Dry weight of 33k lbs seems very light - fully loaded for cruising, I'd expect at least 45k if not 50k lbs According to the ad, the original owners cruised her seriously for 8-years.

On its face, the Beta 75hp is adequate but not ideal so I have to wonder the backstory of repowering with the Beta. There are not a lot of engine options in the 100 HP category. Almost all roads lead to a Deere 4045 (or a variant such as turbo), especially in 2018. I wouldn't be surprised if Deere was the original engine when launched in 2005. But since this was a custom build that apparently took years, maybe they originally used a Perkins - the Beta is a direct replacement so an easier swap. The background - if available - might be interesting

Another tidbit that may/may not be important is the states cruise of 6.3 kts. A realistic cruise on this boat should be 7 to 7-1/4 kts (approx 1.15 * SL). Probably puffery by the broker but given the marginally small engine, maybe not.

If it's an overall good, clean boat, is be okay with the Beta. Not ideal but not a deal killer. But if the background was available, I'd be curious about the original engine and why it was repowered - I'd pay special attention to whether the exhaust system is adequate since the engine is probably very deep in the hull.

Speaking of the engine, I couldn't help but notice there are more pictures of the colorful bedspread than the engine room.

Good luck. It does look like an interesting boat. Especially for cooler climates.

Peter

 

[CharlieO.]

It looks like the listing is by Judy at JWY a member of this forum, maybe she will chime in.

 

[O C Diver]

Simple answer is what's the fuel burn at 6 and 7 knot? If it's 2 GPH or less at 7 knots, I wouldn't be to worried. 20 HP is about 1 GPH. So if it's cruising at 2 GPH, that's about 40 HP out of 60 HP. The trade off may be the engine is running at a higher RPM to cruise at 7 knots. A naturally aspirated JD 4045 is 80 HP at 2,400 RPM. What's the RPM rating on the Beta engine?

In a perfect world, I would want the 4045TFM75 engine with 104 HP and pushing the boat between 1,200 and 1,500 RPM at cruise. That's what my boat did.

Ted

 

[KnotYet]

IMO, the 60HP engine is in keeping with the design philosophy of the Diesel Duck, as in:
modest but adequate power with plenty of fuel to safely go anywhere a boat can go.
My previous boat had a similar WLL, 60% more displacement and was fine with 80 HP.

I like Ducks and have been aboard several, including a 38 that Bill Kimley of Seahorse was
showing at the Pacific sailboat expo about ten years ago. I thought it felt compact but cozy.
If I was still looking at them I'd check out the ones for sale near you in the Seattle area.

 

[sean9c]

It's been years since I read Buehler's book but I seem to remember that I'd thought that he spec'd pretty low hp engines for his designs. You might check his book. My guess is that a lot of builders also thought the spec'd engine sounded like not enough hp so they went bigger. Now that's the norm.

 

[WillieC2]

It's been years since I read Buehler's book but I seem to remember that I'd thought that he spec'd pretty low hp engines for his designs. You might check his book. My guess is that a lot of builders also thought the spec'd engine sounded like not enough hp so they went bigger. Now that's the norm.

Are Sabb engines still available? Reading Buehler years ago really got us to thinking we paupers could get into boating. It worked.

 

[Mac2]

Boat referenced in link:
https://www.yachtworld.com/yacht/1999-diesel-duck-trawler-9785299/


This "41" Foot Aluminum DD is powered by a 60hp Beta Engine. The vast majority of the DD boats I've browsed are powered by 120+hp engines. Any comments on how this boat must perform with such modest power? Are the majority of these boats overpowered? I've browsed several Seahorse boats with 140hp John Deere engines.

You are comparing this aluminum diesel duck (the only one I know of) to the majority of the steel diesel ducks. What is the weight difference? Judy will be able to tell you the rpm’s necessary for hull speed. This should help in figuring out the hp needed to get there.

 

[Judy at JWY]

Here's a bit of background: M/V Diesel Duck originally had a Perkins 78 for power. The new (and current) owner, as of 2013, frequently had trouble when replacement parts were needed - searching for parts, ashore waiting for parts to be found/delivered, etc. Before setting out on his "retirement cruise" in 2018, he was preparing to do a major servicing and realized a rebuild was upcoming which would be parts problematic. So he called George Buehler for George's opinion on repower. George recommended replacing the Perkins with either a 55 turbo or a 60 natural. The owner was concerned with fuel efficiency and simplicity and went with the marinized Kubota - the 60hp Beta engine.

The dry weight of this aluminum DD is 35,000lbs. She burns about 1.3gph at a cruise speed of 6.5knts. The owner says she didn't particularly run faster with the Perkins 78hp turbo. He wanted a slow, fuel efficient safe trawler and he has been very pleased with M/V Diesel Duck and with her performance with her new engine which now has approximately 820 hrs.

 

[KnotYet]

That Perkins Prima M80 turbo diesel bore no resemblance to the 'classic' Perkins 4.236 80hp.
The DD's owner probably made a wise choice to replace it with the Beta 60hp. It's a good one.

 

[jrd22]

Don't know anything about the DDuck but having had a 61hp 4 cyl Volvo in our last 40' sailboat I'd be surprised if they could make hull speed against a 20 knot wind and waves. Seems way under powered, but like I said, don't know anything about the boats.

 

[KnotYet]

Don't know anything about the DDuck but having had a 61hp 4 cyl Volvo in our last 40' sailboat I'd be surprised if they could make hull speed against a 20 knot wind and waves. Seems way under powered, but like I said, don't know anything about the boats.

A sailboat will likely have a smaller and less optimal propeller diameter and blade area,
especially if it has a 'sailing' 2-bladed prop or, worse, a folding prop. Apples to oranges.

 

[O C Diver]

Don't know anything about the DDuck but having had a 61hp 4 cyl Volvo in our last 40' sailboat I'd be surprised if they could make hull speed against a 20 knot wind and waves. Seems way under powered, but like I said, don't know anything about the boats.

I would imagine your limiting factor on the sailboat was the propeller diameter. Most sailboats have smaller diameter propellers as the primary mode is by sail. Larger propellers have a significant drag factor.

Trawlers often have much larger propellers with substantial gear reduction in the transmission. There's a great deal less slippage when traveling in to heavy winds or significant seas.

As an example, my 45' trawler has a 28" propeller and looses maybe a half knot going into 30 knot winds while traveling on the AICW.

Ted

 

[jrd22]

A sailboat will likely have a smaller and less optimal propeller diameter and blade area,
especially if it has a 'sailing' 2-bladed prop or, worse, a folding prop. Apples to oranges.

That's true of a lot of sailboats, ours was a pilothouse/motorsailor with enough prop (3 blade) to need all 61 hp at WOT to run about 1.5 knots over hull speed. Still seems like 60 hp is awfully low for a 45' trawler but I'd guess their fuel economy is great. We burned 1 gal/hr at 6.5 kts. How much hp do you have in your 49'?

 

[North Baltic sea]

Please note that this duck is equipped with auxiliary sails that help it move forward in almost any direction while the engine is running.

I checked my own engine's curves to see at what rpm it reaches 60 hp, and my boat is smaller and lighter. In waves and headwinds, moving forward would be a painful crawl.

 

[North Baltic sea]

I entered the diesel duck data into the engine selection tool and here is the result
In good weather without wind, currents, or waves, 60 hp is sufficient, but if these forces of nature are against you, I would be concerned if I were at sea; you can always stay in the harbor or at anchor.

 

[KnotYet]

That's true of a lot of sailboats, ours was a pilothouse/motorsailor with enough prop (3 blade) to need all 61 hp at WOT to run about 1.5 knots over hull speed. Still seems like 60 hp is awfully low for a 45' trawler but I'd guess their fuel economy is great. We burned 1 gal/hr at 6.5 kts. How much hp do you have in your 49'?

Comparing the Diesel Duck in question to a DeFever 49 displacing around 55k lb and
with probably two to three times the windage is also an apples to oranges situation.
Our DeFever's total HP is 270 but uses only a small fraction of that to cruise at 7 knots.

 

[jrd22]

Still trying to wrap my head around a trawler that displaces around 40,000lbs (fuel and loaded for cruising?) with only 60 hp. Sorry, wasn't trying to compare your boat to the DD, just new to trawlers and with my experience (14 years all over PNW) with our last sailboat with the same hp and about half the weight it's just not working for me, but an interesting boat for sure.

 

[DDW]

Like most cruising sailboats, the DD isn't going to want to be pushed past hull speed. It is a pure displacement hull. My 45' 30,000 lbs sailboat uses about 20 hp to go 6.5 knots, and 75 hp to go 7.8 knots. Wind doesn't change it that much, and current not at all. Where you might want more in the DD is motoring into a significant seaway. Extra thrust there isn't wasted pushing a bow wave, but needed to re accelerate the boat when the next wave knocks 2 knots off of the 5 you've been trying to make.

 

[Mac2]

Still trying to wrap my head around a trawler that displaces around 40,000lbs (fuel and loaded for cruising?) with only 60 hp. Sorry, wasn't trying to compare your boat to the DD, just new to trawlers and with my experience (14 years all over PNW) with our last sailboat with the same hp and about half the weight it's just not working for me, but an interesting boat for sure.

As mentioned above, it’s the larger prop(s) and reduction gear. Maybe you’ve driven a real 4WD (seperate shifter for engaging 4WD). Steep hill in 2WD that’s a struggle. Engage 4WD low and it’s a piece of cake-very slow, but easy. Same principle. Im twin engine, 90 ton and a total of 420hp. That’s less hp than a lot of diesel trucks on the road.

 

[KnotYet]

Still trying to wrap my head around a trawler that displaces around 40,000lbs (fuel and loaded for cruising?) with only 60 hp. Sorry, wasn't trying to compare your boat to the DD, just new to trawlers and with my experience (14 years all over PNW) with our last sailboat with the same hp and about half the weight it's just not working for me, but an interesting boat for sure.

Here's another data point I can offer:
Our old boat, a motorsailer, displaced 30 tons and cruised at its 8 knot hull speed on 80hp.
That corresponds neatly with the 20 ton Diesel Duck doing similarly well with 60hp.
The Duck's hull shape looks like Buehler designed it with efficiency in mind.
Likewise, our Philip Rhodes designed motorsailer, while heavy and beamy, seemed efficient.

 

[Jeff F]

I've put 4000 hours on my 17 ton 50 ft boat. I'd guess that fewer than 20 were at more than 60 HP.

If you're never going to cruise at more than 2 gph there is no need for more HP.