53 Convertible Tunnel Hull

[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