new 36c owner, considering cummins 370b repower

[chrism]

i've been reading this forum for a while now, and like others who have posted - i am very impressed by the expertise and helpfulness of the people here. without exaggeration this forum is the most useful and congenial forum i've come across. reading through the threads here really influenced my decision to purchase a '74 36c because the knowledge accumulated and shared here gave me confidence to take on the project, and because these old hatteras boats inspire passion in so many seasoned boaters. so thanks to the members & sams marine for this incredible resource and community.

my 'new' 36c is nearly all original with 3160 cats. the plan was to not do anything too major this season, but instead go through the whole boat, get everything working and cleaned up. the thinking was, it would be better to learn and use the boat for a few seasons before really jumping in with both feet. just going through and checking/fixing/replacing things is a huge project, as everybody here knows. my buddy is helping (leading) the project, it's over my head but not his. the first part of the project is the engines, we were pretty well into rebuilding the 3160's when i read about the pricing of the remanned cummins, so i am now leaning towards changing the plan and repowering with a pair of cummins 370b's right now instead.

of course, deciding to repower ends up including a lot more than just engines, so before we pull the trigger, i wanted to ask what else i should plan on replacing, and what can wait? i guess we will need new transmissions, a new exhaust system, and new props. i think we should also consider new shafts, slane vents, new fuel filtration, better engine compartment insulation. the original generator should be replaced, since it needs some work anyway, and it will be a heck of a lot easier to remove when the engines are out. i was thinking about going to an inverter-based electrical system, which impacts generator size, so we need to consider putting the inverter in now, too. and of course this is the time to overhaul the wiring (we were planning on doing that anyway), and really clean up the engine compartment. i've also read that people strengthen the stringers when going up so much in horsepower.

i've read every thread on the cummins b's and qsb's and the 36c, and most other threads as well as most of the articles on boatdiesel.com, so i think i've read most of the general wisdom shared on this topic, but if anyone who has gone through a repower or who has the cummins b's can offer any advice, i'd appreciate it. my biggest questions/concerns are about upgrading the shafts, the best way to do the exhaust system, and the sizing of the generator & inverter. also, as a sanity check, i'm looking for confirmation that going with the 370b's today is the smart move rather than waiting 5 years and going with the qsb's. and the 370b's over the 330b's.

the boat is in stuart, florida. it will live at a dock in the manatee pocket, and is currently in the salerno marine 'do it yourself' yard. she's called 'change order 2', but i plan to rename her before putting her back in.

happy to be an old hatt owner and happy to be here,

[67hat34c]

there are 2 36's in your area that were beautifuly done, cummins converts from gas on one of them, also members of this forum.

When do you plan to do the engines?

also be very careful on these old boats, yes they are sold but there are places that cause problems. mainly everywhere there is coring. decks, gunnels the support for the bridge etc. if there is stuff mounted there then you can bet on wet core. Get that stuff out of the way now even if it is not showing. i would still remove all hardware and re-bed it. I found this out the hard way. everthing looked good but it was not, water will leak into an area and not show its ugly head until much later and not in the same place where it is comming in. I recommend working on top side leaks over almost anything else as these cause more problems than you would expect. We just moved from your area in november, have a 34c and just completed the rest of the topside water intrusion problems by replacing all salon windows.

If you dont need to replace the engines right now, if they can be fixed up a little to beat a few more seasons out of them, then clean up the engine room now, degrease etc, keep it clean until the time comes, will make that job go easier at that time.

as far as beefing up stringers for 370's, i dont think there is a need for that unless you are planning on keeping it at WOT in 5' seas. also dont think you need to go crazy with power, these boats are not built for speed, they get squirley. I would think that if you get cruise of 23-25k that should be fast enough. Who realy cares about WOT.

[Paul45c]

I'd ditto that on the speed. Everybody's crazy about it these days, but it introduces problems that you just don't face with original power. Like windows getting torqued and broken, needing rebedding way more often, etc., etc.

I also agree that if at all possible, get some use out of the boat before doing something major with engines. Y'know, it's possible after using the boat one way you suddenly decide after 2 or 3 years that maybe what you really need is model X. Your usage can change.

You've got an ambitious project mapped out ahead of you. You're going to be messing with just about every major system on the boat. And you know already the kind of $$$ that's going to mean. The boat you've picked is a great one, and if it's gonna be the boat of your dreams for a lifetime, you'll get all the enjoyment out of seeing this refit through and reaping the rewards as you run her. But it's a huge commitment in time and treasure. My point? If there's even a slim chance that this is not the same boat you'll have 8 or 10 years from now, you will have said goodbye to loads of dollars you'll never see back when it's selling time. That's really the reality for all of us.

If you want to narrow the scope some and you don't feel you need lots more speed, you may be able to stay with the same gears. That's significant money saved. So is being able to use the same shafts, struts and props. The whole project changes.

But don't let any of us rain on your parade if you're sure where you're going on this. And congrats on the boat! Enjoy.

[whaler23]

Chris, Congrats on your new hatt. My 36C is also a 74 with orig 3160 Cats. As you prob know at 210 HP its no rocket, my cruise is an honest 13-14 knots with a top end around 18-19 depending on fuel, etc... At some point in the 74 model year the 3160 became the 3208. I believe the engines are the same displacement and horsepower in N form. I have had no problems whatsoever from these engines since I have owned the boat. A little smoke on startup which quickly dissipates and smooth reasonably quiet operation. Great on fuel if you can deal with the speed. I had the generator replaced with a new Onan two years ago and repositioned it forward of the port engine to free up more space in the rear of the engine room. A much better location in my opinion. My main investment in the boat was a complete exterior Imron paint job, Canary yellow hull, white topsides. All new pulpit, bow rails, hand rails, hardtop, EZ2CY three sided enclosure, bridge ladder, swim platform, new carpet, cushions, furniture, stove/oven, fridge, head counter and sink, galley counter and sink with faucets, new digital SMX controls for A/C, new Cruisaire units for salon and stateroom and a few other minor things. It's a work in progress as most boats are of this vintage. There is an RO on this site that has two engines listed under parts for sale that also has a 36C, you might talk to him as well about your repower. Good Luck, great boat.

[surfdancer45]

Sounds like you have laid out an exstensive project for your team. The 36C is a great vintage boat and others have pointed out some areas to check. I repowered a 70 model with 300 hp Cummins and have been very happy with the boat (she has been my girl for 23 years). A couple of points for your consideration. Get someone competent to check out your engine room checking the condition of your stringers (the Cummins have a lot of torque and your hull may flex, mine did). Ckeck out the wiring, you may not have to change out as much as you think. The Cummins may require you to move the AC units and the generator. Getting enough fresh air to the Cummins is important so either uprade to Slane's vents or put some blowers in you current vent system. You will probably have to upgrade or increase the size of your shafts and consider adding the newer dripless shaft seals. I did a lot of upgrades to my boat but have done it over the years. Get your engines and engine room right and then tackle the other projects over time. Good luck with your boat and all the projects you will find to do. Bob

[Mike36c]

Chris, congrats on the boat! My 330BTA and a friend's QSB330 are located here on Rocky Point, just a stones throw away. I met you at Shrimper's a few months back but I lost your e-mail address. You are more than welcome to snoop through my engine room and take pictures, I'll also help in any way I can with "do's and dont's". Shearwater had some great boat show prices on reman 370's a while back, BTW the 330BTA and the 370BTA are the exact same engine, they just turn up the fuel and 200rpms for the 370. I return from this trip on Tuesday, let me know. Also, my buddy has almost completed the QSM11 repower and total refit of his 1974 45c located at A&J boatworks, a MUST see.

[the kuz]

Re-powered our 1977 36C with 330 Cummins B series April 2005 (420 hrs now). Like a new boat! Also replaced Onan with new Northern lights gen set. 1.5 to 1 ZF trans turning 3 blade nibrils (22x23). Cruise 23 -25 knts @ 24/2500 turns depending on weight. 28 +/- @ WOT. don't have flow meters, so can't say exactly on fuel, but is somewhere around 20 -22 GPH @ cruise. Get about 3 GPH @ 8 knts (1100 turns). Average 6 - 10 GPH on fills. I opted for 330s vice 370s because of great word of mouth reports from local commercial fisherman about fuel economy and durablity. The motors are very sensitive to fouled props/shafts, so maybe the higher HP 370s are a good idea. Things you will want to consider: Cummins warentee requires factory rep inspection/instrumented sea trial of the installation - you should run new (larger) fuel lines, replace primary fuel filters, add raw water cooling (from engines) to packing glands, new instruments (digital tachs are nice). Your shafts (1 1/2) are fine (be sure they are straight). clean and paint bilge and replace things like old water heater when old motors removed. Check your rudder hardware. Good idea to put new aluminum beds on stringers before new mounts. re-align motors/shafts after a few days in the water. You will remove several thousand pounds on the repower. B series a great fit for this boat. Regards, Bob K

[chrism]

guys thanks for all the advice, lots of good points pro and con. i have to say it looks like we are gonna do it. who knows how long i'll have her but somewhere between 'long enough to wish i could cruise 24k' to 'forever' is my guess. and the price is right. few more days of research and i'll post the plan and any remaining questions.

mike, i'll take you up on that offer to snoop, thanks. i'm up in jersey for a few weeks, i'll drop you a note when i'm headed back. also, i sent you an email a couple days ago, if you didn't get it i can send you a pm.

[Banshee36]

I would go with the 330B's and save a few dollars on the engine purchase.
JW

[Paul45c]

guys thanks for all the advice, lots of good points pro and con. i have to say it looks like we are gonna do it. who knows how long i'll have her but somewhere between 'long enough to wish i could cruise 24k' to 'forever' is my guess. and the price is right. few more days of research and i'll post the plan and any remaining questions.

Well, then hat's off to you and go and get dirty! All the previous cautionary words notwithstanding, it's FUN to get into a big new project like that. Heck, that's why we're all old boat owners in the first place. Just wanted to make sure you knew the score, and it's clear you do. Sounds like that'll be one heck of a sportfish when you're done.