Question? Skipjack Diesel

[riverplayer]

Steve is about right with those numbers but you may be hard pressed to see 26 knots with a single 41 unless you really spend time at propping the boat. We changed over to C2's from the C4's and made the boat light up, and I mean light up! We lost a bit of fuel economy but with the flowscan installed I can dial it in within .1-.2 MPG and achieve the most out of the boat when running loaded up. If you can install the 41 to replace a gasser I would do it in a heartbeat.

[Bank Robber]

Originally Posted by BiggestT

Dean, I initially refrained from answering as I don't have the direct experience you've asked for. After reading this, it sounds like you have all the technical covered for the install. If you're worried about performance figures I'm sure you can readily find gallon per hour figures for the 41 series engines. Even without direct experience with the Skipjack 28 and these engines, I'd feel safe to say that conservatively you're looking at a 20 to 22 knot cruise speed and fuel consumption of 1.5 to 2.0 nmpg, probably closer to the latter. Top speed would maybe reach 26 knots fully loaded. I don't know your mpg figures with the gasers, but I'm sure it was close to 1.0 mpg on a good day.

Your about right on for the gassers I'm getting about 1 to 1. My cruise is about 25 knots at 3500 rpm and wot is and about 34 knots at 4800/5200 per marine power specs with 14x17 props. Lots of speed for a boat of this size but I don't need it. What I need is better mileage and some range. I mostly cruise at 12 knots at night and don't mind taking my time but I do like to pick it up and go if need be. So if I can get 2 to 1 out of these I would be very happy that coupled with the safety factor of diesel fuel make it an easy choice. I just hope the extra weight doesn't cause any problems.

Originally Posted by riverplayer

Steve is about right with those numbers but you may be hard pressed to see 26 knots with a single 41 unless you really spend time at propping the boat. We changed over to C2's from the C4's and made the boat light up, and I mean light up! We lost a bit of fuel economy but with the flowscan installed I can dial it in within .1-.2 MPG and achieve the most out of the boat when running loaded up. If you can install the 41 to replace a gasser I would do it in a heartbeat.

I see that the 41s are compatible with the 1.61 to 1 ratio of my 280s but I'll probably have to do a little fine tuning once I get the engines installed. The 28 is normally set up for 2 engines so I'll be installing 2.


Thanks a lot for info guys.

[BiggestT]

Originally Posted by Bank Robber

Your about right on for the gassers I'm getting about 1 to 1. My cruise is about 25 knots at 3500 rpm and wot is and about 34 knots at 4800/5200 per marine power specs with 14x17 props. Lots of speed for a boat of this size but I don't need it. What I need is better mileage and some range. I mostly cruise at 12 knots at night and don't mind taking my time but I do like to pick it up and go if need be. So if I can get 2 to 1 out of these I would be very happy that coupled with the safety factor of diesel fuel make it an easy choice. I just hope the extra weight doesn't cause any problems.



I see that the 41s are compatible with the 1.61 to 1 ratio of my 280s but I'll probably have to do a little fine tuning once I get the engines installed. The 28 is normally set up for 2 engines so I'll be installing 2.


Thanks a lot for info guys.

Dean, like I said, no direct comparable experience with a Skippy 28 and twin 41 series connected to 280 drives. However, a buddy with a Bertram 28 (wider beam heavier boat) and twin Yanmar 230s on straight shafts gets about 1.8 to 2.0 nmpg, sometimes even better. He can cruise 22 to 24 with a WOT up to about 34 knots (just once). Most of the time he loafs at 20 knots. The Volvo 41s are not as efficient as the Yanmars, offer only 200 hp, but the outdrives will give you better efficiency than the straight shafts, so you make up some there. I know you have a budget not to exceed, but the ideal would be a single D6-310 or even higher in that boat. You could easily see 2.5 mpg with that set up and no doubt it would be merely jogging at 20 knots.

Still, I think you'd be good with twin 41s in that 28 Skippy. Trust me, it will be a world of difference over the gasers. A buddy in the DAC swapped out his old Volvo gaser in his 262 for a KAD43. He says there's no comparison. All of a sudden he's doing extended SCI trips and beyond, where he would never consider such trips before due to range issues. He says it's now a totally different boat and it's opened new horizons.

[piperca]

Dean, I got some info from Grant, as you know. He's repowered a 28 with the 41s and said you'll see better than 2mpg.

Boat Diesel is a good resource, but you'll need to spend the dollars on the membership to get full benefit. I have yet to invest the money.

Diamond Jim, who's a member on this board, has a 28 with twin 31Ps and duoprops. I don't recall what mileage he's getting, but it's pretty darn good. He cruises at 15 knots and can get 20 knots, if necessary ... that's not too shabby! Check your PM for more info on the 31s.

[Bank Robber]

Originally Posted by BiggestT

Dean, like I said, no direct comparable experience with a Skippy 28 and twin 41 series connected to 280 drives. However, a buddy with a Bertram 28 (wider beam heavier boat) and twin Yanmar 230s on straight shafts gets about 1.8 to 2.0 nmpg, sometimes even better. He can cruise 22 to 24 with a WOT up to about 34 knots (just once). Most of the time he loafs at 20 knots. The Volvo 41s are not as efficient as the Yanmars, offer only 200 hp, but the outdrives will give you better efficiency than the straight shafts, so you make up some there. I know you have a budget not to exceed, but the ideal would be a single D6-310 or even higher in that boat. You could easily see 2.5 mpg with that set up and no doubt it would be merely jogging at 20 knots.

Still, I think you'd be good with twin 41s in that 28 Skippy. Trust me, it will be a world of difference over the gasers. A buddy in the DAC swapped out his old Volvo gaser in his 262 for a KAD43. He says there's no comparison. All of a sudden he's doing extended SCI trips and beyond, where he would never consider such trips before due to range issues. He says it's now a totally different boat and it's opened new horizons.

I've talked to a few people about the single engine option for this boat and got 2 opinions. I think the guy who owns Allison Marine had a 28 with a 370hp cummins or yanmar in it and I guess he really liked it. I talked to Grant over at Sea and Ski and he said the mileage would improve but the performance would be lacking. A few other guys over the phone at a couple places have basically said the same thing. I kinda like having a little extra weight down low because of the narrow beam. I may be wrong but it seems it would improve stability.
I'm assuming the Yanmar 230 is 230hp if it is thats quite a bit more hp. I wonder what is the beam and weight of your friends Bertram. I'm guessing 11' and 12000.

Just doing the math.........The last trip we covered 135 miles and so the fuel bill was about $520 with the fuel in the truck and the bait we were right around $720 or $180 per guy. If I can get to that 2mpg range the fuel bill would be reduced to about $290 although a trip to SD would still be $120 a guy, local trips would basically be half the cost and that would be huge.

Originally Posted by piperca

Dean, I got some info from Grant, as you know. He's repowered a 28 with the 41s and said you'll see better than 2mpg.

Boat Diesel is a good resource, but you'll need to spend the dollars on the membership to get full benefit. I have yet to invest the money.

Diamond Jim, who's a member on this board, has a 28 with twin 31Ps and duoprops. I don't recall what mileage he's getting, but it's pretty darn good. He cruises at 15 knots and can get 20 knots, if necessary ... that's not too shabby! Check your PM for more info on the 31s.

I hope he's right Andrew. I'll probably join the other BD (boat diesel) once I get rolling on this project. I'm sure it'll be worth the $25 once I'm actually rebuilding and installing the engines. Good luck with yours and keep in touch.

[BiggestT]

"I'm assuming the Yanmar 230 is 230hp if it is thats quite a bit more hp. I wonder what is the beam and weight of your friends Bertram. I'm guessing 11' and 12000."

You are spot on with that guess on the 230 hp, the 11' beam and the 12000 lb weight for the Bertram 28. That boat was featured on Boat Diesel as Tony Athens did the repower. His typical day local tuna fishing lately is 50+ gallons. A long run down below Ensenada would push 90 to 100 gallons. Your 135 mile trip would be about 70 gallons or less in his rig. At $4.25 a gallon for diesel (my last fill-up was at $4.15 and it's going down further), you're looking at $300 for the boat fuel. It's a significant difference. Trust me, all the guys who have switched to diesel have smiles on their faces. I have never met the person who after seeing or riding on my skiff say they'd rather have it with gas power.

[Waterpup]

Originally Posted by Bank Robber

Just doing the math.........The last trip we covered 135 miles and so the fuel bill was about $520 with the fuel in the truck and the bait we were right around $720 or $180 per guy. If I can get to that 2mpg range the fuel bill would be reduced to about $290 although a trip to SD would still be $120 a guy, local trips would basically be half the cost and that would be huge.

My 24' SkipJack has a single AQD40A and is matched with a DP280. Last trip I put 33 gallons in it and used only 28 gallons on 86 miles or better yet 3MPG. That was around $135 in fuel cost. If you are spending over 4 times what I am you definitely repower ASAP. But then again you already know that.

[Bank Robber]

Well I already have one of the engines I need minus a set of gauges and a rebuild. Now all I have to do is find one more and put in the time and money. So I might as well go for it. Thanks again for the input everyone.

If anyone who actually has this configuration stumbles on this thread of course I'm still interested in the numbers.

[SOUTHWEST]

I've been a member of boatdiesel for over 10 years, and I've owned Yanmar 170 hp diesels for 11. The boat wouldn't be running the way it is without boatdiesel's help. Nuff said.

I have a 27 ft. Albemarle with a dry weight of about 10,500 lb. Add: avg. fuel (1300 lb.), bait water (360 lb.), ice, 3 dudes, and misc and I'm running about 13,700 lb. I avg. about 1.7 nm fishing, and can get 2 nm on a calm day, lightly loaded where I do a lot of trolling. IMO it's the WEIGHT of the boat that will determine its fuel consumption (power plants being equal).

[PaDDy Killer']

My Dad has a 84' 28' skipjack with twin 41's and a pilot house. He gets better than 2mpg and has a 22 knot cruise. Performance is on the low side. Its a lot of weight in a narrow beam. His boat seems to lean when you turn the wheel at cruise speeds. You can't run his boat at full power without the boat leaning and then you start to loose control of the boat. It starts to wonder in one direction. I would think if he did it all over again he would do a big single diesel.

[Bank Robber]

Originally Posted by SOUTHWEST

I've been a member of boatdiesel for over 10 years, and I've owned Yanmar 170 hp diesels for 11. The boat wouldn't be running the way it is without boatdiesel's help. Nuff said.

I have a 27 ft. Albemarle with a dry weight of about 10,500 lb. Add: avg. fuel (1300 lb.), bait water (360 lb.), ice, 3 dudes, and misc and I'm running about 13,700 lb. I avg. about 1.7 nm fishing, and can get 2 nm on a calm day, lightly loaded where I do a lot of trolling. IMO it's the WEIGHT of the boat that will determine its fuel consumption (power plants being equal).

Thats encouraging, I'll have an additional 60 hp between the engines and I believe my boat is about 8000 without fuel. So perhaps with the additional weight of the engines I will get similar mileage. What is the beam on your Albemarle??

Originally Posted by PaDDy Killer'

My Dad has a 84' 28' skipjack with twin 41's and a pilot house. He gets better than 2mpg and has a 22 knot cruise. Performance is on the low side. Its a lot of weight in a narrow beam. His boat seems to lean when you turn the wheel at cruise speeds. You can't run his boat at full power without the boat leaning and then you start to loose control of the boat. It starts to wonder in one direction. I would think if he did it all over again he would do a big single diesel.

Thanks for the reply. I am very interested in hearing more information about your dads boat. If you have a chance maybe you can elaborate a little on the way the boat is set up. Stuff like bait tanks fuel tank capacity and drive type. I would also be interested in how the boat is propped. I would really appreciate it if your or he could give me a call or drop a line here. Thanks

562 477 1445 cell

[ALUMINATOR]

Dean, It is hard to over power a boat and I would also bet a race car. Go fast and burn more. On the other hand replacing yous gas for diesel will only cost you $$$$$. I do not think you will ever be able to off set the difference in fuel savings by changing to diesel unless you run many hours each year! Please don't get me wrong because I run single diesel and love it but I didn't replace I started new when building. I find it hard to believe that by going to diesel you will save 1/2 fuel burn. If that was the case all engines would be diesel. Shoot diesel used to be way less the price per gal than gas but that has changed! I bet you could replace your engines (if needed) with a pair of new gassers and then just slow down when you want to save a buck and you would be way ahead! I bet we are talking gas new for $3-4K each and diesel $15K each.

This is just another opinion to get you thinking.