Hatteras 34 top / cruising speeds?

[VieEnRose]

The model brochures list a wide variety of speeds and weight for the Hatteras 34 (1961-1965). Estimated cruise speed of 25-35 and topping out at 40 sounds good to be true for that generation. What kind of speeds are people seeing with gas inboards? What size prop?

[madhatter1]

40? No way. But before I went diesel on our 34 I cruised 19-20 SMPH at 3200 RPM’s with 454 mercruisers. Never tried higher RPM’s as I thought it was bad for them. But really you can run them quite a bit higher but they will drink gas. At speeds i ran my overall MPG was .7. Top speed was 31 MPH wide open, forgot what RPM we hit. But I will add that with 270 HP Cummins 5.9’s my cruise was 26-27 MPH and same top end of 31. I don’t think the top speed of 31 has to do so much with engine HP but more to due with hull design. My 1300 HP 46 also tops out at 31MPH. I could be wrong but to me it seems like these classic hulls hit a wall around 30.

[UNIQUE_NAME]

i had a 66 34 sedan, not the convertible. someone had repowered her from chrysler 318s to 350 chevy low profile manifold small blocks. wayyyy underpowered.
getting on plane was a struggle and not worth the strain. spent most time as hull speed.
thought about big blocks at one point but it was questionable if they would fit height wise.

[rsmith]

My dad bought a 34SC new it had the 440 290hp Chryslers was a solid 19-20 knot boat but it burned a lot of gas. He added an extra 70 gallons with saddle tanks for a total of 270. He ordered it stripped down for a day fishing boat. Typical mission was a 64NM run to the offshore canyons 4 hours out 8 hours of trolling and 4 home would burn a little over 200 gallons. In 71 we repowered with 3160 cats the same engines that Hatteras was using in the 36 made a huge difference in performance and ride. Cruised at 24 with top of 27. First canyon run was 154gallons plus the boat with the extra speed was way dryer. The 34 had no trim tabs so he put a set on. Big mistake even retracted they slowed the boat down and any extension would bury the bow and start bow steering. Trolling in a following sea the waves wo grab them and pull the stern down really kind of scary. He took them off. The hull design just didn’t need them. It was a great boat I grew up on and we fished way offshore in all kinds of weather never felt there was anything it couldn’t handle.

[VieEnRose]

40? No way. But before I went diesel on our 34 I cruised 19-20 SMPH at 3200 RPM’s with 454 mercruisers. Never tried higher RPM’s as I thought it was bad for them. But really you can run them quite a bit higher but they will drink gas. At speeds i ran my overall MPG was .7. Top speed was 31 MPH wide open, forgot what RPM we hit. But I will add that with 270 HP Cummins 5.9’s my cruise was 26-27 MPH and same top end of 31. I don’t think the top speed of 31 has to do so much with engine HP but more to due with hull design. My 1300 HP 46 also tops out at 31MPH. I could be wrong but to me it seems like these classic hulls hit a wall around 30.

Sounds much more reasonable, the marketing department in the 60's must have had some rounding errors back in the day.

Do you happen to have some pictures of the bottom on yours? Any keel modifications?

Do you remember what props you had with the mercruisers?

[VieEnRose]

i had a 66 34 sedan, not the convertible. someone had repowered her from chrysler 318s to 350 chevy low profile manifold small blocks. wayyyy underpowered.
getting on plane was a struggle and not worth the strain. spent most time as hull speed.
thought about big blocks at one point but it was questionable if they would fit height wise.

That's interesting, is the sedan heavier? I would have guessed that would be ample power to get up on a plane.

[VieEnRose]

My dad bought a 34SC new it had the 440 290hp Chryslers was a solid 19-20 knot boat but it burned a lot of gas. He added an extra 70 gallons with saddle tanks for a total of 270. He ordered it stripped down for a day fishing boat. Typical mission was a 64NM run to the offshore canyons 4 hours out 8 hours of trolling and 4 home would burn a little over 200 gallons. In 71 we repowered with 3160 cats the same engines that Hatteras was using in the 36 made a huge difference in performance and ride. Cruised at 24 with top of 27. First canyon run was 154gallons plus the boat with the extra speed was way dryer. The 34 had no trim tabs so he put a set on. Big mistake even retracted they slowed the boat down and any extension would bury the bow and start bow steering. Trolling in a following sea the waves wo grab them and pull the stern down really kind of scary. He took them off. The hull design just didn’t need them. It was a great boat I grew up on and we fished way offshore in all kinds of weather never felt there was anything it couldn’t handle.

Good to know!

[UNIQUE_NAME]

That's interesting, is the sedan heavier? I would have guessed that would be ample power to get up on a plane.

i dont think so. according to the travel lift guy, mine came in at around 18k.
i think it was much more a case of the small blocks just not having the umph. they only had 260 maybe 270 hp.
the 454 is usually around 330hp.
they could get it on plane but to keep it up there in the 14-15knt range they were screaming.
they turned up to pretty much to top end too, at about 20knt, so it wasnt the props.

[rsmith]

i dont think so. according to the travel lift guy, mine came in at around 18k.
i think it was much more a case of the small blocks just not having the umph. they only had 260 maybe 270 hp.
the 454 is usually around 330hp.
they could get it on plane but to keep it up there in the 14-15knt range they were screaming.
they turned up to pretty much to top end too, at about 20knt, so it wasnt the props.

I should mention ours was a 1965 trunk cabin model.

[UNIQUE_NAME]

I should mention ours was a 1965 trunk cabin model.

those were cool looking boats. i had one across the canal from me a couple of years ago.
always wondered about the space usage on it.