'77 Luhrs 28 ft. diesel repower SPLASHED!

[archbuilder]

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Very interesting project, just came across it....looking forward to seeing your progress. I haven't worked on a boat this size....very cool! Looks like you have things going your way!

 

[fat fanny]

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Luhrs welding does take practice just a balance of heat and feed speed along with the proper arc gap which is achieved with the slight egg frying sound. Build up isn't necessary but penetration is those brackets as said earlier will be under some harsh vibration and stress hopefully they hold untill after your test and then you can address them. I like your project checking on it everyday.

 

[Luhrs28]

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Re: '77 Luhrs 28 ft. diesel repower - just beginning

I decided it was time to buy a couple of batteries and power up the 12V stuff. These AutoZone batteries were on sale and are rated at 1000 cranking amps:

Several things worked right off the bat, and after I cleaned up the corrosion on a bunch of ring terminals more and more things worked. (nav lights, horn, VHF radio, bilge blower, old bilge pump, cabin interior lights, etc.) Here's a shot with the docking lights on:

The previous owner had 6-8 small wires jury-rigged onto each battery post connector, plus some stuff wired with crappy lamp cord believe it or not. So I plan to install a couple of new dual bus bars and organize all the wiring. Also none of the small wires going directly to the battery terminals are switched off with the main switch, so I plan to add new master switches so I can kill the power to everything but the bilge pumps when docked.

Sorry I don't have any more interesting photos but I guess electrical doesn't really lend itself to pictures.

 

[Luhrs28]

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Homemade tool #27: Can anybody guess what it's for?

If you want to loosen the prop nut when there's no engine or transmission holding the other end of the shaft, how're you going to hold the prop from rotating? It worked like a charm:

I realize this post is boring but I feel I have to keep posting my story and pics to keep up with the Starcraft mafia.

 

[sprintst]

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Re: '77 Luhrs 28 ft. diesel repower - just beginning

You're a fabricator like Jesse James now. Just have to lay off the tatooed up broads

 

[sasto]

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Re: '77 Luhrs 28 ft. diesel repower - just beginning

If you want to loosen the prop nut when there's no engine or transmission holding the other end of the shaft, how're you going to hold the prop from rotating? It worked like a charm:

I realize this post is boring but I feel I have to keep posting my story and pics to keep up with the Starcraft mafia.

Not boring at all, Luhrs.

Ever tried a block of wood between the strut and rudder? I carry one onboard just in case.

 

[Huron Angler]

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Good stuff, creative ways to solve the same problem.

I have been thru a smaller version of your wiring situation, it will be nice to know that you've got it all running proper gauge, in the conduit for safety.

Great work as always, this thread is quickly becoming an excellent source of info for any restoration, but mostly huge diesel rigs

 

[QC]

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Hey Luhrs, I just stumbled on this and I am bummed I hadn't before. Love the ride, she's sweet!!

What I wanted to offer was some help with the rating/speed/gearing/performance etc. My background is diesels and I have to say I am concerned regarding performance . . .
From what I can pickup the 6.2 is rated at around 150 hp @ 3600 RPM, the Chrysler 360 is 260 at I am guessing 4200ish RPM. Hence my concern . . . Gear ratio might actually be right, but you're still giving up 100 hp. Have you ever come across some performance numbers for the original setup? I am guessing a 1:1 ratio, do you know? What are your expectations?

 

[pmillar]

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Re: '77 Luhrs 28 ft. diesel repower - just beginning

I love home made specialty tools. You might consider sliding some old radiator hose over the "fingers" to protect your prop from any minor damage or dings in the future though.

And regarding the tranny and HP comments above, couldn't a new prop address differences in rpm sweet spot? It might be interesting to compare peak torque rather than HP as well.

 

[QC]

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Peak torque is not significant to a marine engine except to get her on plane, horsepower is what makes the world go around despite what poorly worded marketing material tries to tell us . . .

A ratio change to .5:1 (OD) can allow us to use a 2100 RPM rated engine where a 4200 RPM engine once was as a bad, but accurate example. If they are both rated 250 hp, and they weigh the same, theoretically they will go the same speed with the same prop. Problem is, there are no OD ratios for typical marine trannys and they don't weigh the same and in this example we are giving up 100 horsepower.

So that brings us to figuring this all out with what we've got . . . Unless there is huge torque rise, which naturally aspirated diesels do not have, then we are not going to benefit much from higher peak torque. Still gottta get her on plane and stay there.

 

[Luhrs28]

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Thanks for all the comments guys! QC you're correct about the HP numbers. My expectation is that the boat is going to be slower than it was with the Chrysler 360, but how much slower I have no idea. My rebuilt tranny has a 1.5:1 ratio, and I believe (but not 100% certain) the original transmission was also a 1.5.

My thinking overall is that the GM 6.2 is real easy to install 'cause there's no turbo and no computer controls needed. I'll run it next summer, maybe mess around with optimizing the prop a little and see how it does. If the power just isn't enough then next fall/winter I'll yank it out and install either a Duramax or Cummins.

One fact of life with my boat is that the engine compartment is only about 29.5" tall under the deck. It was designed for a V8, which is typically shorter heightwise than an in-line engine. The 6.2 diesel V8 is just barely going to fit. A taller engine would force me to have a big hump in the deck, which I'd really like to avoid.

Happy Thanksgiving to everyone!

 

[QC]

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Here's what I am thinking on speed. I did some more searching and found a few running around 20 MPH with the gas engines. I backed down from there and believe you have a 10 inch pitch, maybe 11. Propeller load curves are fairly linear. This means if you forget the steep rise in horsepower required as a typical deep V begins to plane (this is a semi-displacement hull) that the horsepower required goes up in somewhat of a straight line with RPM. If the old engine got to say 4400 RPM I think there is a chance you'll see 3000+ with this one. I am concerned about making the full 3600 though with the current setup, and the pitch is already on the low side so I think I'd like to see a 2:1 ratio. The ultimate point of this mini-ramble is that she may do 12 - 15 MPH and may even plane, but it is on the ragged edge for sure. The semi-displacement hull will allow speeds above "hull speed" and below planing speeds, so she may be just fine and still economical if you can handle the lower cruising speeds. Good luck and I can't wait to see some actual data.

Oh, and the Cummins is bound to be too tall considering your height restrictions. I'd be thinking a 6.5 if you go for another repower. I have done no searching whatsoever, but if there is a water cooled turbo setup for the 6.2 and there is good results from such a combo, that might be the ticket if you need/want more speed. Good luck!!

 

[Luhrs28]

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Re: '77 Luhrs 28 ft. diesel repower - just beginning

The prop currently on the boat is a 16" dia. X 17" pitch, which is the prop used with the Chrysler 360 gasser V8. I need to change it to a L.H. prop to work with my rebuilt tranny, so I'm wondering if I should go with the same size/pitch or change it. I realize this isn't a prop thread but if anybody has any advice I'd like to hear it.

With my 1.5 ratio tranny my prop is only going to turn 2400 RPM max.

Thanks!

 

[QC]

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Re: '77 Luhrs 28 ft. diesel repower - just beginning

OK, I got messed up in post #94 you said 15 inch diameter and didn't know the pitch . . .

Something isn't adding up though. I'm not sure what slip to use, but even at 30% I'm getting above 30 MPH with a 17 and the gasser. I don't believe that.

I'll do some more research and maybe you should start a thread over there, but something is screwy right now.

 

[Luhrs28]

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Re: '77 Luhrs 28 ft. diesel repower - just beginning

QC: Yes I thought it was a 15" dia. just by a rough Stanley tape measurement, but after cleaning the crud off the prop I found it was stamped "16 X 17 R.H."

By the way I'm working on some other boat stuff and will post new pics tomorrow.

 

[Luhrs28]

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Here's a Before shot of the used swim platform I picked up for my boat back in August. I've been saving up a couple of jobs I can work on in my garage in cold weather.

Here's a photo after some sanding, staining and the first of 3 coats of UV-resistant exterior urethane:

Not perfect but it's passable now and at least it's protected from the sun.

 

[Luhrs28]

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Re: '77 Luhrs 28 ft. diesel repower - just beginning

This is the original gauge panel in my boat:

There are no fuel gauges and it's just way too minimalist. So I got some 1/8" thick aluminum and made my own gauge panels.

Here's a shot of the upper one all finished:

I baked the paint/clearcoat on in my kitchen oven, so it's real scratch resistant. One of the few advantages of being divorced is, I've turned almost my entire house into a boat restoration facility and there's nobody to yell at me.

Here's the lower panel with waterproof stereo cover:

If you're wondering what all the extra temp gauges are for, I'm going to have sending units in my transmission, V-drive, and both exhaust risers. I'm sort of obsessed with knowing the temperature of things.

One of the drawbacks to working with industrial machinery is, when I build something it tends to look industrial. I can't help it.

 

[archbuilder]

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Wow very nice work! Looks good, but the architect in me is wanting to see something more.....what about a pin stripe? Or some text that says what the "warning" lights are all about? Ok, enough about the ascetics I'm really enjoying your refit, looking forward to seeing your progress! Its nice to see someone else spending all the money for once! lol!

 

[Luhrs28]

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Arch: Yes I plan to label everything. I'm not sure what's the best way though. Brother P-touch?

 

[fat fanny]

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Re: '77 Luhrs 28 ft. diesel repower - just beginning

Very nice work and I think the embosed labels that are frequent on most industrial machinery would fit the bill.