'60-63 Trunk cabin engines

[SeaSwick]

After much discussion with the broker (& then a mechanic), we've determined that the engines in the '62 41'er aren't 6v71's - as the Forum insisted don't fit in the early trunkcabins - but are 6-53 nats. I'm not looking for a high 20's cruise (close to 20 would be fine), but can this boat get out of it's own way? I mean even get on plane? Sea-trial, survey, & DD certified engine survey would be done, but if this Hatt just pushes a big bow-wave around, I'd like to know to save all the time & effort. Sold
my gas '60 41' (hull #3) due to ethanol issues with her gas engines & fuel tanks... FYI.

 

[Boatsb]

After much discussion with the broker (& then a mechanic), we've determined that the engines in the '62 41'er aren't 6v71's - as the Forum insisted don't fit in the early trunkcabins - but are 6-53 nats. I'm not looking for a high 20's cruise (close to 20 would be fine), but can this boat get out of it's own way? I mean even get on plane? Sea-trial, survey, & DD certified engine survey would be done, but if this Hatt just pushes a big bow-wave around, I'd like to know to save all the time & effort. Sold
my gas '60 41' (hull #3) due to ethanol issues with her gas engines & fuel tanks... FYI.

I have a 41c with the 8v53 naturals and can cruise at 16. With the 6v53 I would expect 12-13

 

[jim rosenthal]

Maybe not plane with those engines, but close. I think 13 kts is about right. Are you thinking about a repower or using her as is?

 

[Avenger]

IIRC hull #1 is now powered with 6V-53Ts and seems to move adequately. Rough math would suggest you're going to need around 600-700 total HP for the kind of speeds you're looking for. I'm guesstimating 28,000 lbs. If you know what these hulls actually displace I can re-run the math.

There's a couple of clips of Knit Wits in this video. She doesn't exactly look like she's ready to go airborne:

 

[SeaSwick]

IIRC hull #1 is now powered with 6V-53Ts and seems to move adequately. Rough math would suggest you're going to need around 600-700 total HP for the kind of speeds you're looking for. I'm guesstimating 28,000 lbs. If you know what these hulls actually displace I can re-run the math.

There's a couple of clips of Knit Wits in this video. She doesn't exactly look like she's ready to go airborne:

Cool clip thanks for passing it along! The early trunkcabins were around 28k lbs, which is why they are such tanks! Many a faster,modern SF would fall behind my Dad's friend's '63 when it got nasty coming back to Montauk, as she'd knock the seas flat. 12-13 could be do-able for a few years until a repower, but is she economical at that semi-planing speed, or would I just be digging a hole in the water?

 

[Avenger]

Do you know the HP of the 6-53Ns? We can re-run the math with that number and see where it ends up.

 

[Boatsb]

200 or 210 if memory serves me.

 

[Avenger]

Using 400 HP total, top end speed should be almost 18 kts. So expect cruise around 14 kts. Remember, this is all in theory. Lots of things conspire to slow boats down.

How did your previous one run at 14 kts? FWIW, I'm usually surprised at how much I can pull back on my 36C without it falling off the step. So there's a good chance she'll run okay. But you would have more experience with them than I do.

 

[SeaSwick]

Using 400 HP total, top end speed should be almost 18 kts. So expect cruise around 14 kts. Remember, this is all in theory. Lots of things conspire to slow boats down.

Thanks for the information. You guys are all on the ball! The 6v53s on her are rated at 210hp each.

 

[jim rosenthal]

I have found, that, too, Scrod. My 36C will stay on plane, or at least partly up, down to about 15-16,but below that she begins to fall off. And that speed will not get her up; you have to go faster and then back it down a bit. Is that what you've noticed?

 

[34Hatt]

Using 400 HP total, top end speed should be almost 18 kts. So expect cruise around 14 kts. Remember, this is all in theory. Lots of things conspire to slow boats down.

Thanks for the information. You guys are all on the ball! The 6v53s on her are rated at 210hp each.

Yes lots to slow it down like people, fuel, water, & tide. My 34c when I got it had Cummins 504's 202 hp and 13 kts was a good day more like 12 kt most days. O.K for most cruising but was pure hell to go offshore in was hard to stay awake coming home after a overnighter. If your cruise close to home not to bad until a re-power I did it for 6 years and sold the drive train motors to props for 5K.

 

[Avenger]

I have found, that, too, Scrod. My 36C will stay on plane, or at least partly up, down to about 15-16,but below that she begins to fall off. And that speed will not get her up; you have to go faster and then back it down a bit. Is that what you've noticed?

I don't normally try to run her there, but yes, climbing out is definitely not the same as pulling back. Next time out I'll keep a closer eye on speed and see where she starts to fall in.

The math says SeaSwick should see an 18 kt top end, so he could (in Theory) put her up and pull back to 14 kts. and stay on top. Some tab will probably be involved there to keep her stern up.

Also, I used 80% as a cruise factor, he may be able to run a set of Ns closer to rated without a problem which would get him to a 15-16 kt number.

 

[Avenger]

Yes lots to slow it down like people, fuel, water, & tide. My 34c when I got it had Cummins 504's 202 hp and 13 kts was a good day more like 12 kt most days. O.K for most cruising but was pure hell to go offshore in was hard to stay awake coming home after a overnighter. If your cruise close to home not to bad until a re-power I did it for 6 years and sold the drive train motors to props for 5K.

That's why I want to live in Theory.

Funny thing about that formula, every time I find a way to reduce drag my boat gets lighter. When the rudders were splayed out like a speed-brake and she topped out at 19 kts the math said the boat was 36,000 lbs. Now that that's fixed and I cruise at 20 kts it's down to about 24,000 lbs.

12 kts to the canyon?!?..... You're dedicated. Was the fish still fresh by the time you got back?

 

[rsmith]

Is the Hull the same as the 64-70 flush deck models?

 

[mderlick]

I have a 1964 41 DCMY, with 653Ns. I rebuilt both of them, and then motored the boat from NC to Toronto Canada this summer (approx 1000 miles). I kept very accurate records as to fuel burn and speed. At hull speed, (8-9 knots or 10 mph) the fuel burn was approx 2.1 gph per engine at 1500 rpm. This gave the boat a range of approx 600 miles. At 13.5 knots (2300 rpm), which is the speed I travelled up the Hudson R. from NYC to Erie canal, and then accross L. Ontario, the fuel burn was
6.5 gal/hr per engine or slightly over 1.1 mpg. Crossing L. Ontario from Sodus Bay to Bowmanville, I used 85 gal. and travelled 96 miles. The waves were 4-6 ft and 45 deg to stern.

Of course, these numbers will change according to the weight that the boat displaces, but all in all, I found the boat to be very economical and reliable. HP RATING: 210 HP OR 195 SHAFT HP.

martin

 

[mderlick]

I have a 1964 41 DCMY, with 653Ns. I rebuilt both of them, and then motored the boat from NC to Toronto Canada this summer (approx 1000 miles). I kept very accurate records as to fuel burn and speed. At hull speed, (8-9 knots or 10 mph) the fuel burn was approx 2.1 gph per engine at 1500 rpm. This gave the boat a range of approx 600 miles. At 13.5 knots (2300 rpm), which is the speed I travelled up the Hudson R. from NYC to Erie canal, and then accross L. Ontario, the fuel burn was
6.5 gal/hr per engine or slightly over 1.1 mpg. Crossing L. Ontario from Sodus Bay to Bowmanville, I used 85 gal. and travelled 96 miles. The waves were 4-6 ft and 45 deg to stern.

Of course, these numbers will change according to the weight that the boat displaces, but all in all, I found the boat to be very economical and reliable. HP RATING: 210 HP OR 195 SHAFT HP.

martin

 

[34Hatt]

Is the Hull the same as the 64-70 flush deck models?

Yes also same for aft cabin also the 34 hull came 4 different ways as in top side.

 

[SeaSwick]

I'm beginning to think my 7', transom bow dinghy with it's 1960 British SeaGull 1.5hp would run rings around this Hatt!

If I were to run her hard (which isn't unusual for me) for 100-125 hours a season for a couple'a years to get near 16-18 knot range detonate the engines? What are repower options? No lightweight, electronic modern iron... don't have $85k to put into a $30k boat! Would need running take-outs... oh yeah & ADDING a marlin tower... 18-20 would be great.

Another thing for you formula guys; what cu ft of air do these engines need? This Hatt has tiny vents on the cabin sides. Feel they should be enlarged.

My 1960 41, with 330hp, 454 Crusaders ran at 22knots (4200rpm I think). Never topped her out & don't know GPH. Only put 20-25 hours on her before she sat for 4 years 'cause of ethanol. She went to Maine for a total rebuild & diesel repower.

I truly appreciate the input.

 

[Daniel]

How are u guys figuring this math to get the speed and is it that accurate?

 

[Canuck Dennis]

My 43 dc with 620 hp tops at 14.2...i fail to see a 41 can do over that with 420 hp. my 2c also, seems he has bought the boat already..