Willard 730 Diesel Repower Project

clloyd · 22 October 2013, 16:39

Well unfortunately my Navy-abused Cummins 6BT only made 40hrs before needing the head off. When we pulled the head, there was severe scuffing of cylinder walls. Basically, that was the end of my relationship with it. I sold it to someone who will rebuild it and make her like new again.

Lesson here is to be very careful buying these boats as you can't really know the internal condition of these engines.

For me, I'm taking the opportunity to upgrade to more horses and speed in general.

Starting this thread to document the repower.

Here's the old one out of the boat and on a pallette.

clloyd · 22 October 2013, 16:56

Here are the existing propping numbers from the 220hp 6BT.

Top
2600 rpm | 29.50kts | 1.43 ratio | Slip 10.5% | 17 1/4" prop | 23 pitch

Cruise
2300 rpm | 25.50 kts | 1.43 ratio | 11% slip

At cruise, burning under 6 gal per hour.

I would like to go into the 300hp range which should give a much higher top end and cruise. Some of the Hurricane interceptors use the Yanmar 315hp. They max at 3800rpm. The new Volvos max at 3500rpm. Cummins max RPM is lower. I am planning on sticking with Cummins for a number of reasons, mostly because the boat is already setup for Cummins geometry and engine mounts. I've learned a lot already about Cummins and I do think they are good engines. Also, the parts are reasonable and the cummunity support is excellent.

The problem with say a 330hp Cummins is that max RPM is only 2950. My transmission is 1:1 and my Konrad 520 drive is 1.43:1. At that gear ratio, I can't go up much on the prop pitch or enough to gain top end.

There are two possibilities to change gear ratio that I know of.

#1 Trade out the Konrad leg for another Konrad at 1.21 ratio.
Pros: Fairly simple change
Cons: Torque to existing tranny (Borg Werner 72C) exceeds max rated torque by a lot. Cummins 330 QSB can put out 814lb/ft. BW gear is rated to 450lb/ft, and that is at max rpm only.
Also torque at Konrad exceeds Konrad max of 738lb/ft although Konrad doesn't seem to worry about that.

#2 Change out BW gear for a ZF280-1 gear with .814 ratio which gives final gear ration of .814 x 1.43 or 1.16:1.
Pros: ZF280 gear can take the torque. Expansion ratio reduces torque to Konrad by 20%. Ratio gives fairly optimal numbers using my existing props
Cons: Custom order ratio, adds cost. Not sure of availability.

Using a 1:16 ratio and 330hp QSB my new prop numbers would be

MAX Speed
2950 rpm | 23 pitch | 1.16 gear ration | slip 10% | 49.9 mph
2950 rpm | 22 pitch | 1.16 gear ration | slip 10% | 47.7 mph

Cruise
2600 rpm | 22 pitch | 1.16 gear ration | slip 10% | 42 mph
2300 rpm | 22 pitch | 1.16 gear ration | slip 10% | 37.2 mph
2100 rpm | 22 pitch | 1.16 gear ration | slip 10% | 33 mph

clloyd · 24 October 2013, 00:08

OK well #1 and #2 options are now out of favor. What a difference a day makes.

Thinking of sticking with the velvet drive 1:1 tranny an possibly getting it beefed up. Finding this a common approach with a lot of the faster boats.

Pitching up in prop and calling it good.

All existing geometry stays the same.

captnjack · 24 October 2013, 00:45

Pretty boat, hope it all works out. I'd love a diesel inboard in this size range.

Bigtalljv · 24 October 2013, 01:08

why don't you stop thinking small and throw a bigger diesel in there with an areneson surface drive and call it good

Jason

clloyd · 24 October 2013, 03:29

It would slash the tubes on the turns

How's yours coming?

clloyd · 24 October 2013, 03:41

Here's the hole.

Sucks to have a boat that is a BIG paperweight, but she'll be right again.

The good thing is that all the geometry should be almost the same by using another Cummins 5.9 block engine.

Take a moment to look at the Gianormous NAVY specified Sea-strainer. That needs to move somewhere else or traded for sane sized one.

6BT is not aftercooled but the QSB is and more hardware on that side of engine.

Exhaust looks huge but it needs to be bigger. Will need a different exhaust port on transom or go with twin ports.

Bigtalljv · 24 October 2013, 04:36

Looks like the arneson's fit on the 11m boats,

http://www.youtube.com/watch?v=fXkj5...e_gdata_player

All of a sudden it seems like things are moving along. The new gas tank is in, and I am getting the transom cap fixed and a handle for the forward hatch fabricated. I'm going to chop up the original diesel tank (gasp!) so I can use the deck top. Then I need to swap trailers and hang the OB. Need to purchase the hydraulic steering system and do some basic electrical. Then it should float and go like a boat

Jason

Bigtalljv · 24 October 2013, 06:17

Arneson Surface Drives

Surface drives, less drag and a lot less money in your bank account

clloyd · 24 October 2013, 15:56

Yeah a lot less.

You'll be excited when those engines are hanging off the transom. That will be a big difference.

On the fuel tank, seems like a shame to chop up. You don't need the vent so why not create a fiberglass plate? Easier to keep painted as a bonus.

I would like to figure out how to install a second kicker tank somewhere. Not a lot of options with the Diesel.

On my tranny, you can get a velvet drive totally beefed up and redone to take a lot more torque. It's out of the boat and on a palette so now is the best time to do it.

Bigtalljv · 24 October 2013, 17:03

the option you have on the diesel is to put a bigger tank in there. I got a 65 gallon and there is a 3" space between the top of tank and the deck level so you should be able to get around 80 in there with diesel. the tank you have only takes up about half the space in there. I thought about fabricating something but the original tank isn't good for anything. They don't wear out so you'd never need mine so I can't sell it, and as you point out they are small. therefore it goes under the knife. all the holes line up and it fits perfectly.

clloyd · 24 October 2013, 19:55

Mine is only 34 gallons!!

Sure you don't want to sell me yours!? I'm headed your way with the boat soon enough.

Can you at least take a picture so I can see the geometry?

ncp · 24 October 2013, 20:48

Quote:

Originally Posted by Bigtalljv

the option you have on the diesel is to put a bigger tank in there. I got a 65 gallon and there is a 3" space between the top of tank and the deck level so you should be able to get around 80 in there with diesel. the tank you have only takes up about half the space in there. I thought about fabricating something but the original tank isn't good for anything. They don't wear out so you'd never need mine so I can't sell it, and as you point out they are small. therefore it goes under the knife. all the holes line up and it fits perfectly.

I'm losing track here Jason....

I thought the tank you pulled that was orig. was 34 gallons:
http://www.rib.net/forum/attachment....6&d=1346641349
(Chris, look how shallow it is. Supposedly another 8 inches available below it when installed)

And you're selling the 85 gallon Moller belly tank:
http://www.rib.net/forum/f47/85-gall...ank-57193.html
(Chris, this wouldn't fit in a diesel since the engine is there)

Jason, you got a new 65 gallon? Aluminum or plastic? Do you think that your welder friend that did your bracket could expand (down) and existing tank?

Bigtalljv · 24 October 2013, 21:29

yes, sorry that was a confusing post now that I read it again. I had a new aluminum 65 gallon gas tank made to fit in the spot where the old diesel was. based on the space above said new 65 gallon aluminum gas tank I think you diesel guys could have a tank of 80 gallon made to fit there.

Looking at the original diesel tank I think you would be better off just making a new one. It's a pretty simple design but welding old aluminum is apparently a crap shoot. Also I think it would be just about the same labor so the only difference would be material costs.

clloyd · 24 October 2013, 21:55

Yeah I think new construction would be the way to go. 65 should be plenty, the diesel is economical. 6 gal per hour at 25 kts or @4 kmpg cruise, 66 gal tank would be 11 hr at cruise speed or @275 nautical mile range.

ncp · 24 October 2013, 22:02

Quote:

Originally Posted by Bigtalljv

yes, sorry that was a confusing post now that I read it again. I had a new aluminum 65 gallon gas tank made to fit in the spot where the old diesel was. based on the space above said new 65 gallon aluminum gas tank I think you diesel guys could have a tank of 80 gallon made to fit there.

Online or local?

Quote:

Originally Posted by clloyd

Yeah I think new construction would be the way to go. 65 should be plenty, the diesel is economical. 6 gal per hour at 25 kts or @4 kmpg cruise, 66 gal tank would be 11 hr at cruise speed or @275 nautical mile range.

Maybe we can get a volume discount; I'll order one too.

Bigtalljv · 24 October 2013, 22:05

online, speedytanks in NJ.

Here it is installed, http://www.rib.net/forum/f45/zodiac-...tml#post578139

clloyd · 30 October 2013, 18:26

Borg Werner Velvet Drive 72c is headed to Florida for upgrade to a heavy duty high performance version.

The standard 72c can handle 500ft/lb torque, this company can upgrade them to into 1500lb/ft range.

BAM Marine Cyborg 1350 & 1500

The QSB 330 can put out 830lb/ft at 1800 rpm.

clloyd · 06 November 2013, 17:18

Hello my pretty. I think you will do just fine.

Brand New engine. Been mothballed in a warehouse. Long story but benefit to me is that it was a good deal. ID obfuscated in photo.

Only problem is, she is 1000 miles away from the boat. Won't be dropped in until January.

Until then, lots of projects to get ready.

Will be keeping the dual 24/12 volt system but will be adding some improvements.

One benefit of a new engine is this engine will start life as a mostly fresh water use engine and I'll only have myself to blame for any lack of maintenance.

clloyd · 16 December 2013, 04:06

Finally the weather has improved and gotten out of the single digits.

Boat is in an uninsulated garage and everything was solid ice.

First thing to go is the MASSIVE bronze miltary sea strainer. Yes it's a great conversation piece but it weighs a ton and takes up half the engine compartment for no good reason.

See the red color in the bowl? That was RV antifreeze and it still froze it was so cold for so long.

Image number 2 shows how tight this boat is in the garage. Radar is 1/4" from top back of garage and bow is 1/4" from other end. Drive is 1/4 from door with prop OFF.