53 Convertible Tunnel Hull

[tpld3]

What was the first year Hatteras started to put prop tunnels in the hull of the 53' Convertible? I thought that the first model year was 1977 but in the thread on Al's boat, I think it was, someone said it was 1976. How did the tunnels affect the speed of this hull? Gain or loss of speed?

Thom

 

[REBrueckner]

David Pascoe says this: "On the later models they added propeller pockets which lowered the shaft angle and supposedly gave a little better speed. "

It would be hard to imagine tunnels that resulted in a slower speed since the tunnels must also add a bit of manufacturing cost.

 

[bostonhatteras]

tunnels reduce planing surface so I think the main advantages are reduced draft and shaft angle. the shaft angle plays a part in efficiency but dont know what percentage. overall its seems a net effect of zero on speed with the only gain being draft reduction.
russ

 

[Maynard Rupp]

Our '86 36C has prop tunnels. The reduced shaft angles make a big difference in performance, but the real advantage is protecting the running gear in a grounding. No longer do you tear the struts out and mangle the props. It is a little hard to sand the bottom paint inside the tunnel though. They are a very good idea IMHO.

 

[Sparky1]

My experience with prop pockets has also been with Sea Rays, but they do result in more speed for a number of reasons. Reduced shaft angle results in more bow lift and more direct thrust. It also ventilates the prop to a degree.

I don't know how sensitve a Hatt would be to such things, but the key to performance with a Sea Ray was proper cupping of the propellers. I knew guys with the same exact boat/power I had, and I could run circles around them because of my props. That obviously resulted in much better fuel economy as well.

That gets back to the ventilation issue as with pockets you are to a degree running a surface piercing set-up. On a go fast boat, the optimum set-up is to split the prop hub where half the prop is running out of the water. I never had any handling problems with reverse even on the largest Sea Ray (55 feet), so I wouldn't expect to have them with a 53C. Then again, I'm sure pocket depth varies between manufacturers.

 

[tpld3]

Thanks for the responses. It looks like the 1976 53C did not have prop pockets, at least not Al's 1976. Was it a change made in late 1976 or in the 1977 models?? One of the things that attracts me to the classic Hatteras boats is the fact that there are so many still around. I do like many things about the interiors of later models but I believe that the older hulls were over-built and I like that. Another attractive thing one is the cost of aquiring a classic Hatteras. I say that when I retire my new job will be maintaining my "new boat".

 

[REBrueckner]

"I say that when I retire my new job will be maintaining my "new boat"."

Having bought a neglected 48ft 1972 YF I can attest to that...Yet after maybe five happy winters of part time restoration,cleaning and equipment upgrades the workload dropped dramatically. You can pour almost unlimited amounts of money into an older boat and I avoided that to some extent by using the boat for full time summer cruising between home port in NY and Maine....Using the boat a lot will point out priorities for your own style of boating that might not come to mind if you have not done a lot of boating previously.

 

[REBrueckner]

I can't imagine, and I may be wrong, that cupped props or surface piercing props would offer any efficiency or speed advantage in a big heavy hull like a Hatt.

In generaly cupping props either adds additional load, reducing top RPM, or enables a smaller diameter prop to be used since the effective pitch is increased. My limited anechdotal knowledge is that they work best on lighter high speed true planing hulls. Tunnels on a big heavy hull like a Hatt likely improve speed modestly, mostly (I think) by offering an improved (lower) shaft thrust angle....If hatt did that as far back as the mid 1970's I was unaware.

 

[GaryNW]

Hatteras' use of prop "pockets" dates back to at least 1974 in the Wynne designed 31'SC and the 1975 31'EC (my ride; same hull as SC). There is a 1974 Yachting article in the brochures archives. Wynne speaks to more efficient use of propeller thrust and allowing bigger engines to set low in the hull for a flush cockpit sole and low profile. I am currently undergoing a repower to brand new Crusader 8.1's. These are several inches taller than my MP 454's due to the intake manifold height. The new down angle ZF 63A's are needed to allow clearance of a little less than 1" to the hatches. Good thing gassers don't need acoustic insulation!
When do we say "tunnels" vs "pockets" or even "scallops" ? I believe there is no official definition, so I propose that if the shaft center is above the hull tangents, we have tunnels. If the shaft center is below the hull tangents, we have pockets. Can I get bipartisan agreement on this?
BTW, my pockets are probably about 6" deep.
Gary

 

[tpld3]

"I say that when I retire my new job will be maintaining my "new boat"."

Having bought a neglected 48ft 1972 YF I can attest to that...Yet after maybe five happy winters of part time restoration,cleaning and equipment upgrades the workload dropped dramatically. You can pour almost unlimited amounts of money into an older boat and I avoided that to some extent by using the boat for full time summer cruising between home port in NY and Maine....Using the boat a lot will point out priorities for your own style of boating that might not come to mind if you have not done a lot of boating previously.

I know well how much work it is restoring boats in the 50 ft size range. The last boat I restored was a 50 ft steel hulled trawler. Fifty feet can be twice as big as forty feet when it comes to the complexity of the combined systems. There was very little that I had to enlist the expertise of professionals to accomplish. I studied and asked and made mistakes which were often educational over the last thirty years of messing with boats. I often watched as other less mechanicaly inclined owners paid poorly trained "professionals" to do repairs and installs on their boats. While there are not alot of choices in Alaska, there are some very knowledgable pros. When it came to welding, upholstery, painting, wiring, fiberglass work, engine swaps, woodworking, I did the work with the help of family. While I got very tired of long days I did find the work very satisfying, more satisfying that retail.

Having worked on steel, wood, and frp boats I found aspects of each type to have benefits. At this time of my life, however, I am most likely going to limit my ownership to frp boats. I almost made the move to Florida once to restore an aluminum Broward but I came to my senses.

As for the prop pockets or prop tunnels, the idea that the lesser angle of the shafts are more efficient makes sense. I don't necessarily see any other benefit besides draft reduction from prop pockets.

 

[Sparky1]

I can't imagine, and I may be wrong, that cupped props or surface piercing props would offer any efficiency or speed advantage in a big heavy hull like a Hatt.

In generaly cupping props either adds additional load, reducing top RPM, or enables a smaller diameter prop to be used since the effective pitch is increased. My limited anechdotal knowledge is that they work best on lighter high speed true planing hulls. Tunnels on a big heavy hull like a Hatt likely improve speed modestly, mostly (I think) by offering an improved (lower) shaft thrust angle....If hatt did that as far back as the mid 1970's I was unaware.

Like I said, I'm not sure it would matter that much on a Hatt either as it's not a true planing hull, but I would never have imagined how much difference it made on my Sea Ray 345 Sedan Bridge. I dinged the props pretty good on that thing and had them repaired at a very reputable shop. First time I ran it with the "new" props, it would turn the proper RPM, but it wouldn't get out of its own way. Turns out, they took out all the cup on the 18 x 18 wheels. Of course they claimed their repair was perfect, and the problem I had with reduced speed was not their fault.

I took the props to another shop who acknowledged they needed to be cupped in order to perform properly on a Sea Ray. Sure enough, he called the factory, got the specs for the cup, and my speed came back after installing them. They just weren't getting the right bite without the cup. I'd bet that was the problem with Craig's gas hog he talked about.

 

[Sparky1]

I wish that had been the case Sparky, but I went the same route, calling SR getting the correct cup etc., I even gave 4 bladed props a try. It was a fine boat, but was a gasser, with 454's. A very thirsty combo. Talking with other 34' SR sedan owners they found the same to be true. Coupled with small tanks 100 gal. ea., gave her very short legs. My old 42C Hatt deisel, is quite a bit cheaper to run.

I know some of these guys get upset when Sea Ray's are mentioned, but which year model 34 Sedan did you own?

Mine was a '88, and unlike the previous 34DB's, it didn't share a common hull with the Sundancer. They only built them for two years, '88 & '89 with the '88 being a single stateroom. It held 250 gallons of fuel and was also powered by 7.4 MerCruisers. All things considered, it was quite fast and economical. It would cruise an honest 30MPH at 3,500 RPM and net about .9 MPG. Displacement speeds would net over 1MPG. I knew two other guys who had this same boat, and I really could run circles around them. Maybe mine was just a freak or something.

 

[Sparky1]

I came very close to purchasing a new '86 340DB but found out it had small blocks after driving across two states to sea trial it. The seller, a Sea Ray dealer, advertised it has having 350 Crusaders. They were 350's all right as in 350CI (270's) vs 350's which is how Crusader designated their 454's back then. The boat ran surprisingly well with those small engines, but I decided to hold off and wait.

As for your 34 vs the one I had, I'd bet mine was heavier as it was definitely a wider beam than the previous generation. Could be the hull design was more efficient, but they dropped it after a two year run.

Yeah, this is a Hatt forum, but the topic was about prop tunnels. May as well share our experience with them huh? Beats the hell out of talking politics on a boating forum. I love my 41, but I do miss that 345DB sometimes.

 

[tpld3]

I sent an email to Hatteras asking about prop pockets. Below is their reply:

Thom, thanks for you email. The 53c never had prop pockets installed on them. We did not start this type of installation until the mid 90's. Make sure you are speaking to a 53c, if you have the HIN number of the boat in question I can probably give you a more definite answer.


Cecil M. Meadows
Director, Customer Service
Hatteras Yachts
(252) 634-4809

While I have no reason to doubt this, I do wonder about the differing draft of various years of the Hatteras 53C in listings of boats for sale.

Thom

 

[86Hat41]

Hatteras originally put the pockets in to make room for the larger propellers needed for the 12 cylinder engines.
Heard this from a VERY reliable source.

 

[tpld3]

Hatteras originally put the pockets in to make room for the larger propellers needed for the 12 cylinder engines.
Heard this from a VERY reliable source.

But did they ever put them in the 53C and if so, what was the first year they did so?

Thom

 

[Sparky1]

I sent an email to Hatteras asking about prop pockets. Below is their reply:

Thom, thanks for you email. The 53c never had prop pockets installed on them. We did not start this type of installation until the mid 90's. Make sure you are speaking to a 53c, if you have the HIN number of the boat in question I can probably give you a more definite answer.


Cecil M. Meadows
Director, Customer Service
Hatteras Yachts
(252) 634-4809

While I have no reason to doubt this, I do wonder about the differing draft of various years of the Hatteras 53C in listings of boats for sale.

Thom

But did they ever put them in the 53C and if so, what was the first year they did so?

Thom

Looks like you answered your own question as the 53C was only built until 1980. I doubt very seriously prop pockets were introduced solely to handle larger diameter props.

 

[tpld3]

Not much gets by you Sparky.

 

[saltshaker]

mid to late 70's 53C's have prop pockets. I have seen several and always heard that those with pockets are preferred. I think you got some bad info from Hatteras.

 

[tpld3]

Thanks Jack. I wonder if anyone at Sam's might know exactly what year they started using them. I read somewhere it was 1977 and was just trying to verify this. I'll keep digging.

Thom