56' MY can it plane>

[kjcampos]

hello all we have a 1981 56' MY and was wondering if this boat can be made to go up on Plane... 4 do any other 56' owners make their boat Plane i would really like to know if its possible to do that on this model we have tried many times but can never get enough speed to seem to push the bow down... yes we use the Trim Tabs ...the best speed we have gotten with this boat was 15knts in the Tampa Bay flat calm and just out of the boat yard with new bottom paint...we always keep our bottom clean so thats not the problem...we just had the props tuned and prop speed at General Propeller in Bradenton Fl. we told them our issue and they calculated and repitched the props from 30x29 to 30x28 4 blade said it would help but nothing happened ....we have DD 8v-92ti and our WOT is 2200-2250 RPMs...any ideas?

 

[q240z]

Sounds like you might be overpropped. I believe those engines should be propped to 2350~2400rpm WOT.

 

[saltshaker]

WOT should be 2300-2350 fully loaded

 

[SKYCHENEY]

Sounds like you might be overpropped. I believe those engines should be propped to 2350~2400rpm WOT.

I believe that is correct. You should turn 2350 loaded. I'm sure the boat planed when new or they wouldn't have sold them to anybody. Weight, engine condition, and bottom condition are all factors as well.

 

[Boatsb]

3000 lbs of personal items may be one of the factors too. I've looked at a few boats over the years that seem to loose more and more speed only to find they have more stuff in there than I have in a 4 car garage.

 

[SEVEN]

You are absolutely right Bob, I sold my last boat and when we finished unloading the boat it raised 3 1/2 inches. We had over loaded it for 18 years. My new Hatteras is being keep light weight. My wife isn't happy.

 

[bobk]

I well know the weight issue. My 48 was advertised as 44,000 pounds dry. One haul out had it at 53,000 and that was for a summer layup in 2014. It adds up fast. Fortunately we do not want to go fast.

Bobk

 

[kjcampos]

ok we have emptied our water tanks ...350gal x 8.36 lbs = 2962 lbs ... but we have added a 13' Boston Whaler with 40 hp engine on top less then 1000 lbs boat was made for that...we had a sectional couch that weighed a lot took 4 people to take it off we now have 2 couches that weigh less then the one we took off combined...we don't have a lot of personal stuff except your normal stuff sheets towels and some of our clothes in the galley normal stuff from pots to dishes and food items ...i'm sure Hatteras took that into account when they build the boat i hope...about being over propped according to General Propeller i am under propped they told me i should be 32 x 30 4 blade ..we do try to run with full fuel tanks as much as possible n less the 50 gal. in the holding tank ...i do carry 15 gal. of extra motor oil
i understand about not being 2350 WOT but thats just 150 RPMs less is that making that much of a difference ....i guess i will have to tell the wife she needs to take all her bathing suites off the boat and i guess i have to take all the liquor off too...but my cigars stay...

 

[kjcampos]

I well know the weight issue. My 48 was advertised as 44,000 pounds dry. One haul out had it at 53,000 and that was for a summer layup in 2014. It adds up fast. Fortunately we do not want to go fast.

Bobk

Bob we do not want to go fast either ...we only do 8 -10 knts at between 1200 - 1350 RPMs depending on the current we burn 10 gal an hour we like the fuel economy ....but when it starts to get bad outside would like to know that we could get on plane and do 18 knts ? ...don't care about the fuel burn...so we could get to a safe place faster...

 

[Boatsb]

Cigars have a low enough density to be left aboard.

The real question now turns to 2 things.

Engine performance. Are they healthy and strong or are you carrying 5000 lbs of water in the keel or somewhere.

 

[kjcampos]

Cigars have a low enough density to be left aboard.

The real question now turns to 2 things.

Engine performance. Are they healthy and strong or are you carrying 5000 lbs of water in the keel or somewhere.

my engines are very healthy and strong i keep on top of them change the oil and filter every 150 hrs and change the oil filter in between the oil changes.. my bilge areas just have the little water the pumps won't pump out....i am constantly using the manual switches to pump out all the bilge areas and have the wife looking to see there is no more water pumping out of the boat ....where and how would i get 5000 lbs of water in the keel ...i thought the boat was solid Firberglass from the water line down....does Fiberglass observe water???? could putting bigger Trim Tabs make a difference...we looked at a Hatteras 56' in Lighthouse Point FL ..before we bought this 56'...and it had some kind of SS extension under the swim platform between the Trim Tabs and the broker told me it was to help make the boat plane easier...by the way we offered full asking price for that boat and the owner would not sell it....

 

[bobk]

I may have missed it... is the rpm measured with a photo tach on the engine or gage at the helm? And that missing 150 rpm might be what is needed to get on step after which it can be backed off.

Bobk

 

[kjcampos]

I may have missed it... is the rpm measured with a photo tach on the engine or gage at the helm? And that missing 150 rpm might be what is needed to get on step after which it can be backed off.

Bobk

yes with a Photo Tach my mechanic did it when we did a sea trail before we bought the boat and after i had the props tuned....by the way my mechanic did tell me that it was low 150 RPMs on the engine survey....never paid much attention to it was not ever planing to go up on plane...yea right silly me.....lol

 

[Pascal]

Like most boats back then, all of our boats are underpowered and it doesn't take much to loose that final 10% performance which you need to get it up on plane. And then you have the cooling system which needs to be 100% up to the job.

Start with basics. Make sure the tachs are accurate, make sure the trim tabs come fully down and check your engine control linkages to ensure they go all the way

Then look for those missing 100/150 rpms... Tune the same engine, maybe use a IR thermometer to make sure all cylinders are giving all they got

But bottom line you can't expect a 30 year old boat and 30 year old engines to perform as new and it doesn't take much to loose that edge.

 

[rsmith]

Is that Georges old boat? GLH? Incentive? Thought he'd chime in by now

 

[saltshaker]

If you were under propped your RPMs would be high not low. That means there's something wrong with the data or the engines. 150RPMs is a lot to be off. Have you done a no load test? Make sure they hit 2450-2500 no load. If not you need to find out why. Weight would be the next thing to look at if the engines and running gear are set up properly. Water in the keel is something you may not notice as the top of the keel is closed. Does the water line look low compared to other 56MYs? Making these boats plane takes all
They've got but they should be able to do it.

 

[kjcampos]

Like most boats back then, all of our boats are underpowered and it doesn't take much to loose that final 10% performance which you need to get it up on plane. And then you have the cooling system which needs to be 100% up to the job.

Start with basics. Make sure the tachs are accurate, make sure the trim tabs come fully down and check your engine control linkages to ensure they go all the way

Then look for those missing 100/150 rpms... Tune the same engine, maybe use a IR thermometer to make sure all cylinders are giving all they got

But bottom line you can't expect a 30 year old boat and 30 year old engines to perform as new and it doesn't take much to loose that edge.

Pascal just had the Heat Exchangers and the Intercoolers removed and cleaned and new Impellers on new water pumps installed on both engines did sea trail and cooling system working 100% we have all new Garmin electronics with Trim Tab indicators and they say 100% down ...they should read right?..we have checked the Tachs to the engines with the right equipment n they are reading right have done the IR thing and even changed the injectors... engines are running good...i'm very anal about keeping them to their best...i've asked my mechanic about overhauling them and he said i was crazy they are running fine...so guess just have to except the fact of them being 30 + years old they are doing their best...yes it was Georges old boat and she is in GREAT SHAPE...we make sure of that....
Jack i have not seen any other 56' since we bought ours and when we were looking to buy not something i looked at...will have to do the no load test when we get home to FL...i thought there might be other members here with 56' MY

 

[Walter P]

When the 56 MY came out I fell in love with it. To me it was like a 53 on steroids. I do recall that there was much written about the earlier models lacking the power to get up or stay on plane. I seem to remember that the later 56's had a little more power then Hatteras decided to extend the mold to 58'. The 58 performed much better and it was attributed to the extra 2 ft of length. It has long been discussed that the 58 YF with the same engines and load as the 53 MY is a little faster then the 53 MY. While I'm not a marine architect or navel engineer, I do know that long and skinny is generally faster than short and fat.

You mentioned that another 56 had what appeared to be extensions of some sort under the swim platform. I would suspect that that was an effort to add to the planing length in order to get up on plane. In 1980, Hatteras ordered that the new 43 DC and TC (yes they did make a triple cabin) have the 6-71 TI's detuned down to 325 HP because they were afraid that it was too fast and could potentially get an inexperienced new owner in trouble. The 1979 model was a little heavier, like the earlier models so the higher HP engines were OK. Starting in 1980 Hatteras engineers decided to use less resin and came up with a new layup schedule thereby reducing the weight but it also necessitated lowering the available power to prevent trouble in following seas etc in the hands of some inexperienced new owners. At that time they also drastically reduced the size of the trim tab planes to prevent too much lift aft which would have the same concerns. The result was that it was still a decent performer but not like what it could be capable of. How do I know about this? I had two 43's one earlier model (1973 DC) and later a 1980 triple cabin. I had the engines brought up to what they should have had power wise and probably most important, we extended the trim tab planes substantially. The results were dramatic. By now everyone's wondering what all this has to do with Joe's 56. Well, to me it seems that Hatteras had a good boat in the 56 but a better one with the 58 (as far as performance goes). The 56 (especially the earlier models) had a tendency to squat and have difficulty getting over the "hump" whereas the 58 MY did not.

Joe, I believe that you have several issues, one of course is not reaching the proper RPM's which as was stated on previous posts could be a prop problem or the engines need some attention. These issues should be pursued and corrected and that may be all you need to do but I would also look into having new heavy duty longer trim tab planes made and installed. The folks at Bennett or other tab manufacturers should be able to help calculate the cylinder strength factors etc.

I don't want to open a can of worms on this issue, but all the above can be substantiated. I recall discussing it with Steve McPhearson while sitting in his office at the High Point Hatteras plant which was well prior to him establishing SAM's marine.

BTW, none of our boats were intended to be speed boats but the ability to plane and scoot away ahead of bad weather in my opinion is to me an important consideration.

Walt

 

[saltshaker]

There could be many things at play here so you need to attack this one at a time. Start with the engines. 150RPMs light is significant and if they're being overloaded that will shorten life significantly. If you're running at hull speed you'll be fine for now. The no load test should be the first step and should have been done at survey and before any prop work. You may be adjusting your props the wrong way. Do it yourself. All you need to do is run the engine WOT in neautral and see if it hits 2500. If not then you can start chasing down why. Could be as simple as throttle linkage.

 

[kjcampos]

Walt you are very right she squats when we try to WOT her she can't get over the hump...lol....i have also asked this question to Bruce Morrison and he also told me that i need longer Trim Tabs ...we don't want to go fast just would like to know we can to move out of the way of a storm if possible