More power?

[stormchaser]

As we have loaded the baot down with full live aboard gear and now have full fuel tanks...we can no longer plane off. She just doesnt have enough power to get out of the hole. I have the 425hp 8v71`TIs...is there any way to get a bit more power out of them? How will it effect longevity? I dont plan on running them hard all the time, but it sure would be nice to be ab le to plane off shen I want/need to get somewhere on a schedule.

 

[jmccubbin]

Dave,

You have 435 hp 871ti's. The boat always had Stanadyne in the tanks as a fuel treatment. Stanadyne provides a slight increase in performance (5%) and fuel economy (8%). You should look into it if you are not treating the fuel. It also helps with longevity of the new low sulfur fuels and the motors smoke less and the transom stay's cleaner are it takes care of the small particulates. Just my 2 cents but we found it really worked well. It was the fuel treatment that we always used. Jim

 

[SLIDELLBIGAL]

I would say your getting all you can out of a 8V71 at 435 hp, You can put 115 injectors in it but then its going to be a hand grenade if you don't melt it down first.

Capt Kirk "we need more speed Scotty"

Scotty " thats all she's got Capt. but I'll see what I can do"

 

[stormchaser]

Dave,

You have 435 hp 871ti's.

Same thing as the 425s...it is jsut a matter of whether you want to call the 425 or 435, Brokers seem to like calling the 435. haha! As far as treatment goes, we put in AJX-TCS at fill up...but I'll look int6o adding some Stanadyne, Its really a matter of weight...she is HEAVY now. Lots of live aboard stuff plus full tanks...

 

[MikeP]

Hard to imagine you could put so much weight on that she won't plane at all if everything is ok - engines/clean bottom/clean props/shafts.

When I say it's hard to imagine, I guess what I'm really saying is that I can't imagine you could have more cr@p...er, I mean necessary boating equipment than we do, and our 435HP 53MY will plane though it takes it a while to do so and she'll fall off plane at just a bit under full throttle RPM.

It seems that most 53s I have heard of (ours, certainly) require full down trim tabs and WOT for up to a full minute to plane. I ran into a problem where ours wouldn't a few weeks ago because I had turned off the trim tab breaker doing some work and had forgotten about it so the tabs weren't working.

I wouldn't recommend you do anything to the engines OTHER than ensuring they are functioning correctly/tuned to spec. The engines should have N90 injectors - I suppose it's possible that a PO installed something smaller...

 

[stormchaser]

Well, she PARTLY planes. Our top speed is now about 15.5 knots versus 17.9 from sea trial. But at sea trial she was empty as far as "stuff" is concerned, almost empty water tanks, and 1/2 tank fuel. Lets see...what did we had...

- Full time live aboard clothing, wife is a clothes horse and ahs DOZENS of pairs of shoes on board.
- All sorts of kitchen gadgets, pots, pans, plates, cast iron cookware, etc.
- tons of miscellaneous "crap"...err...necessary boating stuff.
- A second dingy (Avon RIB 10' with 9.9hp outboard
- A cast iron and tile table on the aft deck
- A full sized Weber Genesis gas grill on the flybridge
- Full water tanks
- Full fuel tanks

If you don't think that's enough...I'll have to investigate further..everything SEEMS ok....engines run up to correct RPM, run hot but not TOO hot at WOT (about 195 is where they settle after 20 minutes, seems like its about time for a heat exchanger cleaning), bottom, props,shafts were just done at a short haul...Other than MAYBE problems with the tabs not fully extending...I cant think of anything other than weight?

 

[jim rosenthal]

I think you've diagnosed your problem accurately.

Are you new to the liveaboard lifestyle? Seems to me there are two ways to approach this: the first is to have everything you own and/or think you might use on the boat with you, second is to have a storage locker and keep all the stuff that isn't immediately necessary in there. I lived aboard for quite a few years. My rule (copied from an article I read in one of the local boating journals) was that she had to be ready to go out in half an hour, all the time (unless I had a major project underway). So I kept everything I didn't really need right then in my storage and the boat was lighter and much easier to take care of. Maybe you need to lighten ship a bit....

 

[MikeP]

After reading your posting, I agree with Jim, I think it's just weight. Our 53 doesn't have a non-full closet or storage space and we do have silestone countertops, etc. But we don't have any BBQ or second dink so I suspect you are faced with either not cleanly planing or asking the Admiral to reduce the load...

Hmm, given those choices I'd figure on not planing.

 

[stormchaser]

Hmm, given those choices I'd figure on not planing.

Yup, that's the answer. lol I'm okay with that, my previous live aboard was a 40' displacement hull trawler (Willard). I'm used to a 7.5 knot cruise, so even loaded down, this boat seems FAST.

 

[REBrueckner]

435 is brake HP, 425 is shaft HP.

Are you turning recommended 2300 RPM at WOT? If not you are not developing maximum prop HP nor speed.

Keep your holding tank EMPTY.

Carrying a big dinghy and large outboard?

Sure your props and bottom are clean? Stabliziers may also slow you a half or a whole knot.

Are you running with big alternators and high outputs...or powering refrigeration with belts?

Why not run slower with full fuel and water, consider faster cruise when you are lighter. Each gallon of diesel fuel is about 8 lbs or 800 lbs per 100 gallons.

Prop scan or the equivalent might also yield you maybe 1% or 2%.

How about permanent wedges to boost your stern up or spray lift rails.

yes you can modify your engine for extra HP, but it does affect longevity if run at high cruise RPM. A 46 Bert sportfish I know got an extra two knots when he had larger injectors put in his 1972 8V71TI's....maybe other modifications were also required....and such a change will further strain your cooling system so it needs to be clean and proper for such a change.

You could consider removing stub shafts and extra props if you carry them aboard.....

Empty lower tanks and install a watermaker...or if you have a watermaker and don't use it, get it off???.

Two generators...unload one??

"it sure would be nice to be able to plane off shen I want/need to get somewhere on a schedule."..... is one of the most dangerous things you can do on a frequent basis!!!!!

Don't know your budget, but ten knot cruising is usually a pleasure and economical !!!!

 

[Traveler 45C]

How about permanent wedges to boost your stern up ..

What are these ane where are they installed?

 

[MikeP]

I would expect permanent wedges, just like tabs fully down, would help you get on plane but would decrease hull speed efficiency. Why not just keep the tabs so you can do whatever works best for the speed you are operating. Tabs also allow you to balance the port/star trim. Can't imagine the weight savings would amount to all that much...

 

[SLIDELLBIGAL]

I had my welders fab up these 1/4 inch Stainless trim tabs after I felt that the factory fiberglass ones were flexing.

 

[SLIDELLBIGAL]

here they are

 

[sandspur1966]

Sweet! That is the modern equivalent of old timers "putting a little hook" in the bottom of old wooden downeaster's to get some lift.

I agree that this is a weight issue more than a lift issue. Remember that all that weight is cumulative and builds up quickly. In the interests of family bliss i wouldn't look to save weight by limiting extra shoes. but you would be surprised, if you start keeping track, by how much weight you can pull off the boat with things you truly don't need.

When I bought this last boat I took of over 300 lbs in old wiring, electronics and plumbing from equipment no longer installed (yes I kept a running tally) Not to mention another few hundred in old used zincs and bronze plumbing fittings.

I would suggest taking a notebook and inventorying each stateroom and storage location with the intent of culling back unnecessary "stuff."

Keep track of it and you will be amazed!

Finally if budgets allow you may want to examine current choices on tenders, redundant systems etc. Ask yourself for instance "do I really need an ice maker on the aft deck the flybridge and one in the galley?

 

[Brian Degulis]

If your turning full rated RPM but not making the speed you should you might be under proped. Typicaly a boat that won't plane because of weight won't hit rated RPM. It's possible your props are to small or have had pitch taken out of them. So the governer stops the engine @ 2300 but the rack is not in full fuel and your not developing rated HP. You can check that by removing the buffer screw on the governer housing running the boat up to WOT and using a blunt wood stick like an un sharpened pencil. Go thru the governer screw hole and push on the fuel lever if the rpm rises more than 50 your under proped or under pitched. 195 is to hot.

Brian

 

[Walter P]

Years ago when Frank Huckins was still around and running his facility in Fla, his boats were known to be fast (they still are). When a client would buy a new boat it was always checked out personally by Mr. Huckins before it was delivered. Every now and then a customer would bring his boat to the Huckins yard and complain that he lost some speed. Mr. H would have the customer leave the boat for a day or two and do his magic on it. A couple of days later the customer returned to retrieve his boat and would ask if they found the problem, to which he was assured that they in fact had found and corrected it. When asked what it was he was directed to a large pile covered with a canvas drop cloth next to the boat. When the guy looked under the canvas he found all sorts of "stuff" that was previously stored aboard.

This is a true story and it happened a lot. I agree that your problem is clearly a case of putting ten pounds in a five pound bag. You can have one or the other but with the engine power we have relative to our boats, we can't have both.

Walt

 

[stormchaser]

If your turning full rated RPM but not making the speed you should you might be under proped. Typicaly a boat that won't plane because of weight won't hit rated RPM. It's possible your props are to small or have had pitch taken out of them. So the governer stops the engine @ 2300 but the rack is not in full fuel and your not developing rated HP. You can check that by removing the buffer screw on the governer housing running the boat up to WOT and using a blunt wood stick like an un sharpened pencil. Go thru the governer screw hole and push on the fuel lever if the rpm rises more than 50 your under proped or under pitched. 195 is to hot.

Brian

Thanks...she's CLOSE to being properly propped. She IS slightly over propped, by about 100rpm. I will double check the pics from the sea trial and see if maybe I lsit a little rpm or not, but if I did, it isn't much. I plan on getting the props redone via propscan, but she DID plane off and top out at close to 18 before we loaded her down and nothing changed with the props.

I am confused by the 195* is too hot part...I thought the "never exceed" was 205? What should she settle at after a good long run at WOT? Cruise speed she sits right at 185*.

 

[ron6785]

I am cruising with my 53my and have 871 naturals, we're liveaboards and there is no way this boat will plane. Part of the reason is my trim tabs arn't operational, but the real reason is I just don't have enough ponies to get her up so why try. My bottom and props are clean but I'm not sure even if the boat were empty with naturals I could get her up on top. Must Admit I wish I could every now and then just because its a guy thing. She will push up to about 14 which is trying really hard but can't see any benefit in that unless there is some real reason to burn that much fuel for so little increase in speed.

My guess is that with your engines everything has to be perfect Jupiter and Mar in alignment and the Boat in the Seventh Sun to get her up when loaded Like we are. Ron

 

[stormchaser]

As long as the engines are running properly, I guess I'm ok with no longer planing. I cruise around 9 knots anyway. I just got a rush when she was up on plane during sea trial and when we brought her home after purchase. It fel like a freight train to be going that fast on something so big.