Enghulline placement in a downeast

BillD

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Engine placement in a downeast hull

Hello ALL,

I was reading/reviewing some older posts from noreast.com and this forum.
I came across "powderpro's" (Brian) great thread on building his 34 Calvin Beal with Cummins QSC 500 power.

The speed during seatrials for this 34 Calvin were impressive. Brian suggested in a post that "maybe" the placement on the QSC more aft in the hull than rountinely done in a 34 Calvin Beal "may have" helped with the seatrial speeds.

I also noticed in the seatrial pics and the video of the boat running that the "running attitude" of his build was relatively flat.

I've also read many posts by owners and builders that "many DE hulls do not like carrying weight forward. Holland's boat shop has built the 32 with v-drives placing the engine further back in the boat.

And we see many DE hulls with engines half in/half out of the forward cabin.

Many forum members (and me of course) are searching for the 28-32 ft DE boat that will cruise an easy 20-22 knots. We know Brian's 34 Calvin Beal could. I'm sure there's a 36 NB that can do 20-22 knots, John's 36 Flowers can.

Is it possible to gain speed in a DE hull by moving static (engine) weight to the aft of the boat?

Let's open the discusions !!!!!

Bill D


Saltwater Fishing Discussion Board Including Inshore Fishing, Offshore Fishing, Saltwater Fly Fishing and Kayak Fishing

Saltwater Fishing Discussion Board Including Inshore Fishing, Offshore Fishing, Saltwater Fly Fishing and Kayak Fishing

Powderpro's post back in 2010

"Definitely a home run, although I'm not surprised with how light the boat is, how flat the stern is, and how much power the engine produces. That 8.3 Cummins has some serious power. I don't know what the weight of the boat is, but my dad and I were guessing around 14,500 pounds at sea trial. When loaded with fuel, gear, etc, probably about 17,500 pounds. I wish I knew what the weight was, but I don't know. What I do know is the boat jumps out of the water when you give it throttle.

One thing that is different on my boat than most other CB 34's is where we placed the motor. Calvin Beal Jr. suggested a 12'6" shaft length. I'm assuming most, if not all CB 34's have about that long of a shaft. I placed my engine farther aft with a total shaft length of 9'10". So my shaft is 2'8" (32") shorter than what is probably typical. I'm not saying that necessarily helped my numbers, but it may have. My dad and I believe in keeping weight out of the bow of the boat, and the engine is the heaviest single item in the boat, besides the fuel."

The CB 34 called SEACOCK participates in some of the lobster boat races. I think he told me that his engine produces around 540 hp, he has the same reduction as me (1.75:1) and the same or similar shaft length as mine does. He runs a 3 blade prop (mine is 4 blade) and I think he tops out at about 37-38 mph. His boat probably weighs about what mine does, but my cabin is taller and grabs a little more air.


This post edited by powderpro 10:13 PM 07/05/2010
 
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GoodChance

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I can only add to this conversation with some real world experience. I friend of mine on Smith Island MD was building a 36BHM with a Cat 3208t at 320. Blue Hill told him "mount the engine xx feet from the transom (i forget wahta the number was but it was pretty close to center of the hull). Anyway, he wanted it further aft by about 6ft. So he did. Crusie speed was an easy 20kts at 2400rpm ..... very quick for a 36BHM with just 320hp. The cabin was small and light as well. The fuel tank was forward of the engine.
 

WoundUpMarine

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mudhake

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I did a 32 holland that was a loaded boat with a 315 cummins with a zf v drive and the thing scooted right along.
 

BillD

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I did a 32 holland that was a loaded boat with a 315 cummins with a zf v drive and the thing scooted right along.
Thanks for the input Steve.
I figure too that with the engine weight aft of midships a DE hull "might not dig" it as much bow wise and dart around as some owners have mentioned ???
 

BillD

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I did a 32 holland that was a loaded boat with a 315 cummins with a zf v drive and the thing scooted right along.
Steve, curious??

Where would the engine "sit" in the helm cabin/cockpit of a 32 Seaworthy with v-drive??
Would make a nice engine box seat!!! LOL
Sure would keep the weight out back ??
 

BillD

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I can only add to this conversation with some real world experience. I friend of mine on Smith Island MD was building a 36BHM with a Cat 3208t at 320. Blue Hill told him "mount the engine xx feet from the transom (i forget wahta the number was but it was pretty close to center of the hull). Anyway, he wanted it further aft by about 6ft. So he did. Crusie speed was an easy 20kts at 2400rpm ..... very quick for a 36BHM with just 320hp. The cabin was small and light as well. The fuel tank was forward of the engine.
Chris?
Your buddy must have had a pretty tall engine box.
Was there a winterback on the 36 BHM?
If so was the engine forward or aft of the partion??
 

Powderpro

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Since Bill dragged me into this discussion;), I might as well respond. In my opinion, the placement of the engine is dependant on a lot of different factors; like the design of your hull, the weight of your engine, fuel tank location, the weight and placement of your cabin, the weight and placement of your gear, food, generator, etc, etc. In my particular case with the 34 CB, my steering bulkhead was roughly 18" - 24" forward of where a typical commercial lobster boats would be. So to translate, the weight of my cabin was farther forward than average or "normal", so to counteract that, I moved my engine back a little. I also believe in having as flat a shaft angle as possible, so a shorter shaft will produce a steeper shaft angle, but I was running a 26" prop, which produced a shallower shaft angle then if I had been running a 28" prop. As a reference point, the very front of my QSC was about 8" forward of mid-ship. The boat was 34' long, the front of the engine was about 17'8" forward of the stern. When I build my 38'8" long Wesmac, I'm thinking the engine will be about 18" forward of mid-ship.

If I were to build another 34 CB, I would definitely go with a 28" diameter prop (a 28" will just fit under a 34 CB), and if I went with another QSC, I would probably go with about an 11' shaft length. I don't think it would have hurt or altered the performance of my particular boat if the engine was placed 1' ahead. Going with the bigger diameter prop would require moving the engine ahead a little bit to keep the same or similar shaft angle.
 
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BillD

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It was worth it

Since Bill dragged me into this discussion;), I might as well respond. In my opinion, the placement of the engine is dependant on a lot of different factors; like the design of your hull, the weight of your engine, fuel tank location, the weight and placement of your cabin, the weight and placement of your gear, food, generator, etc, etc. In my particular case with the 34 CB, my steering bulkhead was roughly 18" - 24" forward of where a typical commercial lobster boats would be. So to translate, the weight of my cabin was farther forward than average or "normal", so to counteract that, I moved my engine back a little. I also believe in having as flat a shaft angle as possible, so a shorter shaft will produce a steeper shaft angle, but I was running a 26" prop, which produced a shallower shaft angle then if I had been running a 28" prop. As a reference point, the very front of my QSC was about 8" forward of mid-ship. The boat was 34' long, the front of the engine was about 17'8" forward of the stern. When I build my 38'8" long Wesmac, I'm thinking the engine will be about 18" forward of mid-ship.

If I were to build another 34 CB, I would definitely go with a 28" diameter prop (a 28" will just fit under a 34 CB), and if I went with another QSC, I would probably go with about an 11' shaft length. I don't think it would have hurt or altered the performance of my particular boat if the engine was placed 1' ahead. Going with the bigger diameter prop would require moving the engine ahead a little bit to keep the same or similar shaft angle.
To drag you into the discussion :rolleyes:

I and others have learned some good intel.

I'm thinking of bolting the new QSB 6.7 into a 32 MC "engine belts facing aft", tranny facing forward !! LOL
Get that engine weight back where it belongs and keep the shaft angle flat !!!! pr. of side saddle tanks and off we go !!!!
 

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Bill- Having the engine aft would definitely make the cabin more quiet and the V-drive could create a flat shaft angle. Just do it :wink:. You won't regret it.
 

mudhake

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bill d, sorry for the late reply, I have been doing a repower in 36 bhm tuna boat. 3208ta cat out a new 550hp qsc cummins in. Totaly depends on the hull as far as engine placement and how much fuel and the amount of ammenities you put in the boat. The 32 h&h will carry the weight forward just fine. If you went with a v-drive you could slide the tanks farther forward and actualy carrie more fuel. Its all about knowing the hull, where everything is placed and balanced, and what the boat is going to be used for,and what kind of weight is going to be carried on the aft deck.
 

BillD

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bill d, sorry for the late reply, I have been doing a repower in 36 bhm tuna boat. 3208ta cat out a new 550hp qsc cummins in. Totaly depends on the hull as far as engine placement and how much fuel and the amount of ammenities you put in the boat. The 32 h&h will carry the weight forward just fine. If you went with a v-drive you could slide the tanks farther forward and actualy carrie more fuel. Its all about knowing the hull, where everything is placed and balanced, and what the boat is going to be used for,and what kind of weight is going to be carried on the aft deck.
Got it ! Thanks !
 

BillD

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Since Bill dragged me into this discussion;), I might as well respond. In my opinion, the placement of the engine is dependant on a lot of different factors; like the design of your hull, the weight of your engine, fuel tank location, the weight and placement of your cabin, the weight and placement of your gear, food, generator, etc, etc. In my particular case with the 34 CB, my steering bulkhead was roughly 18" - 24" forward of where a typical commercial lobster boats would be. So to translate, the weight of my cabin was farther forward than average or "normal", so to counteract that, I moved my engine back a little. I also believe in having as flat a shaft angle as possible, so a shorter shaft will produce a steeper shaft angle, but I was running a 26" prop, which produced a shallower shaft angle then if I had been running a 28" prop. As a reference point, the very front of my QSC was about 8" forward of mid-ship. The boat was 34' long, the front of the engine was about 17'8" forward of the stern. When I build my 38'8" long Wesmac, I'm thinking the engine will be about 18" forward of mid-ship.

If I were to build another 34 CB, I would definitely go with a 28" diameter prop (a 28" will just fit under a 34 CB), and if I went with another QSC, I would probably go with about an 11' shaft length. I don't think it would have hurt or altered the performance of my particular boat if the engine was placed 1' ahead. Going with the bigger diameter prop would require moving the engine ahead a little bit to keep the same or similar shaft angle.
Brian,

You put a 1.77:1 gear/26" prop in the old 34 CB/QSC 500.

You stated "if" you were to build another with a QSC 500 you'd go with a 28" prop. What would you use for a gear? 2:1 or better ??

Also, why change anything? You had the old 34 CB dialed in pretty good.
Slow the shaft speed down a bit with a bigger prop/lower gear?

Finally, If you built a 34 CB (same as the old 34 CB) with a QSC 550, what prop and gear and what speed do you think you'd get out of the boat with the extra rpms?

Curious,

Bill D
 

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I think the QSC 500hp is an excellent engine for the 34' Calvin Beal. At under 2,000 lbs bobtail, I would consider it a fairly lightweight engine for it's power output, and is a nice compact design. Everybody makes a 9 liter 500hp engine, so you have lots of choices, but the Cummins is a nice, proven design. I would go with 2:1 reduction, 28" diameter prop (probably 29" of pitch) , and about 10'6" - 11' shaft length. If you go with a deeper reduction like 2.20 or 2.5, your 28" prop would be quite a bit oversquare, and if you were spinning a 26" diameter, you would be way oversquare. 2:1 reduction is perfect if you want to use a 28" prop, and 1.77:1 if you go with a 26" prop (assuming a light weight 34 CB with 500hp engine like the Cummins, Deere, Volvo, Iveco, or Cat). With 1.77:1 reduction, 2,600 rpm redline, 26x27 Michigan Dyna-Quad, would have been about 95% load. At sea trial I had no gear on board and was light on fuel, and the prop was 26x28 and load was about 97%. The prop needed to be dropped to 27" of pitch, and would have been perfect once I got more fuel and gear on board.

In a bare bones basic 34 Calvin (like mine was), I don't think there is going to be much of a difference in the top speed between a 26" and 28" prop. A 26" prop is very efficient in a basic light weight 34' Calvin. Get a little weight in it, and the 28" will outperform the 26", but you would get great performance with either prop, in my opinion.

I personally would get the 500hp version. The 600hp version is a 3,000 rpm engine, so to get the extra hp, they are increasing the rpms, but you aren't getting any more torque. The 600hp version is a waste of fuel in my opinion. Torque spins the prop, and the 500hp is rated at the same torque. The 500hp will probably have the same or better cruise speed as the 600hp.
 
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BillD

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I think the QSC 500hp is an excellent engine for the 34' Calvin Beal. At under 2,000 lbs bobtail, I would consider it a fairly lightweight engine for it's power output, and is a nice compact design. Everybody makes a 9 liter 500hp engine, so you have lots of choices, but the Cummins is a nice, proven design. I would go with 2:1 reduction, 28" diameter prop (probably 29" of pitch) , and about 10'6" - 11' shaft length. If you go with a deeper reduction like 2.20 or 2.5, your 28" prop would be quite a bit oversquare, and if you were spinning a 26" diameter, you would be way oversquare. 2:1 reduction is perfect if you want to use a 28" prop, and 1.77:1 if you go with a 26" prop (assuming a light weight 34 CB with 500hp engine like the Cummins, Deere, Volvo, Iveco, or Cat). With 1.77:1 reduction, 2,600 rpm redline, 26x27 Michigan Dyna-Quad, would have been about 95% load. At sea trial I had no gear on board and was light on fuel, and the prop was 26x28 and load was about 97%. The prop needed to be dropped to 27" of pitch, and would have been perfect once I got more fuel and gear on board.

In a bare bones basic 34 Calvin (like mine was), I don't think there is going to be much of a difference in the top speed between a 26" and 28" prop. A 26" prop is very efficient in a basic light weight 34' Calvin. Get a little weight in it, and the 28" will outperform the 26", but you would get great performance with either prop, in my opinion.

I personally would get the 500hp version. The 600hp version is a 3,000 rpm engine, so to get the extra hp, they are increasing the rpms, but you aren't getting any more torque. The 600hp version is a waste of fuel in my opinion. Torque spins the prop, and the 500hp is rated at the same torque. The 500hp will probably have the same or better cruise speed as the 600hp.
Brian,

Is the prop aperture "big enough" to spin a 28" prop without "rumble".
Also, did you measure or have a guess what the shaft angle number is with a 9'8" shaft you had? And can you keep the same shaft angle with a 10'6" or 11 foot shaft?

Would you use saddle tanks on either side of the engine or one big tank behind the tranny for better weight distribution. 200 gallons is plenty for my use. Resale?? not sure what to put in for tankage.

The reason I'm asking all these questions is I've come to the conclusion that a 32 ft or shorter DE hull, no matter who's design, will not get me the solid every day 22-23 knot cruise no matter what I put in for power.
The 34 CB built spartan as I'd use it will get the speeds I'm looking for easily.

Plus, your old CB34 and the Seacock BOTH have a low bow attitude @ cruise speeds with a shorter prop shaft. (I've seen the pics)

Still "shopping".:D

Thanks, Bill D
 
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Powderpro

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Bill- Stewart would be the best one to ask about prop rumble using a 28" prop. I noticed the last 2- 34 CB's have installed the 28" prop. Don't quote me, but I think the 34 CB has about 33" of apeture (check with Stewart on that), so if you went with 3.5" of prop clearance from the hull, you would have about 1.5" of clearance on the skeg. Calvin Beal's own 34 has a 28" prop, so I know it will work.

As I've said before, my 26" wheel had 2.875" of clearance from the hull (could have and should have had more clearance) and the boat ran very smooth with no noticeable rumble, and that was with a prop with no cup.

My shaft length was 9'10", so if you jump up to a 28" prop, and you go with say a 10'10" length shaft, your shaft angle should be almost exactly what mine was with the 26" prop. A larger diameter prop will require a steeper shaft angle if the shaft length remains the same. I really think a 10'6" - 11' shaft length would be what you want if you go 28" prop and QSC engine. Calvin Beal recommended a 12' - 12'6" shaft length 4 years ago when I was ordering the hull, and with a lightweight engine like the 6.7 Iveco, a 12' shaft would work fine in my opinion, plus the Iveco engine is shorter in length than the QSC or other 9 liter options.

As I've said numerous times before, the 34' CB is the best boat available under 36'. It will cost the same money and require the same amount of work to finish the 34 as it would a 31 or 32 if you have the same power. And the 34 Calvin is a bigger and more capable boat than the 32's.

A 200 gallon tank behind the transmission a few feet would be a fine place to install the tank. My 220 gallon tank was closer to the stern, but only because that was where it had to be. My center fish hold was where the tank should have gone if you wanted a perfect balance, but fish hold capacity was more important to me than fuel tank placement. 200 gallons is a fairly small tank for a 34' boat, but I don't think it's so small that the resale would suffer greatly. I would recommend putting in a little more fuel capacity (like 250 gallons), but it's your boat, not mine. And plus, just because the tank is 250 gallons doesn't mean you have to fill it up. On my Alaska boats, I put in as much fuel capacity as will reasonably fit, and I never have more than 225 gallons in my tanks. The boat I just built has a 400 gallon tank, and I will never put more than 225 gallons in it.
 

BillD

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Bill- Stewart would be the best one to ask about prop rumble using a 28" prop. I noticed the last 2- 34 CB's have installed the 28" prop. Don't quote me, but I think the 34 CB has about 33" of apeture (check with Stewart on that), so if you went with 3.5" of prop clearance from the hull, you would have about 1.5" of clearance on the skeg. Calvin Beal's own 34 has a 28" prop, so I know it will work.

As I've said before, my 26" wheel had 2.875" of clearance from the hull (could have and should have had more clearance) and the boat ran very smooth with no noticeable rumble, and that was with a prop with no cup.

My shaft length was 9'10", so if you jump up to a 28" prop, and you go with say a 10'10" length shaft, your shaft angle should be almost exactly what mine was with the 26" prop. A larger diameter prop will require a steeper shaft angle if the shaft length remains the same. I really think a 10'6" - 11' shaft length would be what you want if you go 28" prop and QSC engine. Calvin Beal recommended a 12' - 12'6" shaft length 4 years ago when I was ordering the hull, and with a lightweight engine like the 6.7 Iveco, a 12' shaft would work fine in my opinion, plus the Iveco engine is shorter in length than the QSC or other 9 liter options.

As I've said numerous times before, the 34' CB is the best boat available under 36'. It will cost the same money and require the same amount of work to finish the 34 as it would a 31 or 32 if you have the same power. And the 34 Calvin is a bigger and more capable boat than the 32's.

A 200 gallon tank behind the transmission a few feet would be a fine place to install the tank. My 220 gallon tank was closer to the stern, but only because that was where it had to be. My center fish hold was where the tank should have gone if you wanted a perfect balance, but fish hold capacity was more important to me than fuel tank placement. 200 gallons is a fairly small tank for a 34' boat, but I don't think it's so small that the resale would suffer greatly. I would recommend putting in a little more fuel capacity (like 250 gallons), but it's your boat, not mine. And plus, just because the tank is 250 gallons doesn't mean you have to fill it up. On my Alaska boats, I put in as much fuel capacity as will reasonably fit, and I never have more than 225 gallons in my tanks. The boat I just built has a 400 gallon tank, and I will never put more than 225 gallons in it.
Brain,

As always, thanks for your input.
I recall Will Byrnes had rumble issues with his 34CB a few years back. Pretty sure he was swinging a 28" prop, 5 blade maybe. But his 34 CB weighed in @ 22,500 lbs.

I relooked @ all your posted numbers on noreast on the 34CB you built.
To me, I'm not sure I'd change what you did with the running gear.
QSC 500, intermittent duty, cruise can be 200 off the top (2400), 26" prop, 1:77 gear.....run the boat between 2200-2400 rpms and I'm pretty much assured a solid 22-23 knots with a boat that "might top out loaded" @ 16,000 lbs.

The Kelley Anne, a 34CB with a QSC 500 built by Farrins, topped out @ 28-29 knots and I KNOW the Kelley Anne was built heavier than I'd ever run the boat with gear. Also, if you notice the Kelley Anne's "bow up attitude", it "seems to my eye" to be a bit higher than F/V Mayor and Seacock.

The Kelley Anne has an 8" "step up" to the helm cabin and has 6'2" of MAX headroom. I can live with a 4"-6" step up and have 6'4"-6'5" in the helm cabin.

I'm not quite sure how much "step up" the 34CB needs over a QSC 500 while keeping the cockpit floor as low as possible and not having an engine box.

More procrastination!!!!!!:D

Bill D
 

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cb34

Very few owners ever actually put their boats on a scale. If you have never put your boat on a scale your only quessing, and nobody quesses high. When my 34 was built our educated and estimated weight was 5000lbs light. Now Bill, the Kelly ann nor any other 34 finished as a pleasure boat runs 29-30Kts. Mine ran 24 with a perfectly clean bottom and conditions. If you wanted to run 22-23 knot cruise you would be at WOT and be burning a ton of fuel. The beauty of these boats are their simplicity and efficiency. Yes you could put everything in them, bolt on a big motor and push them hard while you dump fuel . But I understand now that is not what they were born to do. Just my 2 cents that depreciated even more today;)
 
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