46 Convertible refit begins

[Mick c]

Until I saw this post, I was tempted to make a joke about "that's not a refit...THIS is a refit" (pronounced in Mick Dundee fashion...knife scene in NYC, with a link to my Roamer post.It's been my experience that with enough effort, you can get good running Cummins Diamonds and gears in that price range, but I don't know if 450~480hp is enough to push the Hatt 46. With the skill set you and your mate bring to the game, I think you'll be able to pull it off for that overall budget.As to whether or not you can do it in 2~3 years...I hope you do, and I'll be watching every update! But if you splash before me, I'll be very impressed! lol

Lol I know that scene in the movie very well. Yes I think we will need about 600 hp. We are very much filled with hope and optimism at the moment so I also hope that doesn’t change. Thanks for showing interest. M

 

[Mick c]

Until I saw this post, I was tempted to make a joke about "that's not a refit...THIS is a refit" (pronounced in Mick Dundee fashion...knife scene in NYC, with a link to my Roamer post.It's been my experience that with enough effort, you can get good running Cummins Diamonds and gears in that price range, but I don't know if 450~480hp is enough to push the Hatt 46. With the skill set you and your mate bring to the game, I think you'll be able to pull it off for that overall budget.As to whether or not you can do it in 2~3 years...I hope you do, and I'll be watching every update! But if you splash before me, I'll be very impressed! lol

I just checked out your entire blog and yes you defiantly have the bigger knife. Fantastic project and really well done. Really looking forward to seeing your progress. Regards Michael

 

[jim rosenthal]

You ought to see it in person. What he's done is amazing. I have seen several refits done in professional yards which don't get close to what he's done working alone, teaching himself along the way.

 

[Walter P]

Thanks Mick for keeping us in the "loop" on your refit. We all look forward to watching the restoration
of one of our favorite boats. Please post progress report with lots of pictures...

Walt

 

[Mick c]

Thanks Mick for keeping us in the "loop" on your refit. We all look forward to watching the restorationof one of our favorite boats. Please post progress report with lots of pictures...Walt

Thanks Walt, we will defiantly post photos as we get some progress. We are only working on the boat on the weekends so progress is slow. Just the strip out is quite a big job but I must say very satisfying to do. Thanks for your interest in our project. Michael

 

[Mick c]

You ought to see it in person. What he's done is amazing. I have seen several refits done in professional yards which don't get close to what he's done working alone, teaching himself along the way.

Hi Jim, we intend to do a trip to the us to go boat spotting so we just might do that. Next year sometime I would say. Michael

 

[Mick c]

Dont do anything until you have a plan. It's not the best idea to start without a complete plan.Engines depend on what you want in performance and the hull will need mods to go to higher HP engines.

Hi Scott,What type of mods need to be carried out on the hull. We are trying to spec the drive line to achieve 30 knots ?

 

[scottinsydney]

Hi Mick,

I have been following all your emails and the replies from other owners. You must show photos as forum members pour over them.

Did you mean myself, scottinsydney, regarding drivetrain mods and achieving 30 knots? If so then I need to tell you that I am a motor yacht kind of guy and use a speedboat for the kids' thrills and spills.

The answer to your question relates to horsepower, shaft size and propping. The Convertible members could do the calcs for you. There may be a maximum speed the hull is able to achieve too without becoming unstable/tailwalking

30 knots on Sydney Harbour?...oh yes please!

 

[jim rosenthal]

I don't know what sort of performance Hatteras got from the 46 convertibles; I know that there was a high-performance version with 8-92s in her, I think, and those boats were faster. Those kinds of speeds (thirty knots plus) are easily achieved with the 45 Series 2 convertibles, which have a different hull form and I think are a bit lighter. I don't know if 600hp x2 will get you to thirty knots. I don't know what Series 60s weigh. Part of the advantage of the Cummins M11s is that they are lighter engines, esp for the power they deliver, but they are also much more money.

My uneducated and imprecise guess is that you could get to a 25 knot cruise without too much difficulty. 30kt cruise might be quite a bit harder. You would be limited by shaft size, how much room there is under the boat for the wheels, hull form, all the underwater hardware. On the plus side, some of the best driveline manufacturers (Veem, Austral) are right in your backyard, so to speak, so you will have access to all the best technology, probably less expensively than we get it up here. Regardless, it's going to be a very interesting project.

 

[Pearl Island]

I don't know what sort of performance Hatteras got from the 46 convertibles; I know that there was a high-performance version with 8-92s in her, I think, and those boats were faster. Those kinds of speeds (thirty knots plus) are easily achieved with the 45 Series 2 convertibles, which have a different hull form and I think are a bit lighter. I don't know if 600hp x2 will get you to thirty knots. I don't know what Series 60s weigh. Part of the advantage of the Cummins M11s is that they are lighter engines, esp for the power they deliver, but they are also much more money.

My uneducated and imprecise guess is that you could get to a 25 knot cruise without too much difficulty. 30kt cruise might be quite a bit harder. You would be limited by shaft size, how much room there is under the boat for the wheels, hull form, all the underwater hardware. On the plus side, some of the best driveline manufacturers (Veem, Austral) are right in your backyard, so to speak, so you will have access to all the best technology, probably less expensively than we get it up here. Regardless, it's going to be a very interesting project.

I have a 45 Series 2 convertibles with Cummins QSM11 660hp 2" shaft that I purchased in New Orleans area 4 years ago. At sea trial in Lake Pontchartrain, we reached 30 knot@2,350 rpm. After taking the boat to Rep. of Panama, I found it over-propped and could only get 26 knot@2,200 rpm (for some [FONT=arial, sans-serif]reason it happens with many boats when they are moved to Rep. of Panama, maybe due to high humidity, I do not know).
I have now gone from 28x32 prop to 28x30 and to 28x28 prop and get 26 knot@2,350rpm and ithe engines are also right on the fuel curve, I have also added a dinghy.[/FONT]

 

[madhatter1]

I have a 1982 46 HP with the 8-92's. Top speed is 27 KTS but not getting full RPM either due to a less than honest bottom diver or it seems port side not getting full throttle or both. Was told it was 30KT boat new. Cruise is 20KTS at 1750-1800 RPM.

A similar HP modern engine would give same top end but higher cruise since they can run higher RPM's than a DD at cruise. I would guess a 23-24KT cruise which IMO is plenty fast. If serious fishing I could see the need for higher HP and speeds. Otherwise we are quite happy at 20KTS. Owners preference and needs are the deciding factors.

 

[Mick c]

Hi Mick,I have been following all your emails and the replies from other owners. You must show photos as forum members pour over them.Did you mean myself, scottinsydney, regarding drivetrain mods and achieving 30 knots? If so then I need to tell you that I am a motor yacht kind of guy and use a speedboat for the kids' thrills and spills.The answer to your question relates to horsepower, shaft size and propping. The Convertible members could do the calcs for you. There may be a maximum speed the hull is able to achieve too without becoming unstable/tailwalking30 knots on Sydney Harbour?...oh yes please!

Hi Scott,Ive been struggling a little with the forum format but I’m just starting to get my head around it. I agree that I need to post more photos and I will try and get them on tonight. I did try and post a video but I couldn’t seem to get up there.Maybe I’ve got the wrong Scott? I did see a post to me which commented on tailwalking above around 26 knots. He mentioned some mods to the hull as our hull is not a HP version unlike ( Good Grief ) which I have seen and read a lot about.It’s not that I really want to do 30 knots but it seems like a good number to target. The boat is out at Glendenning now so if your ever around I would love to catch up with you to discuss all things Hatteras. I am picking up a new Brigg Eagle 8 in November so alternatively it would be great to swing by and have a look at your boat. Regards Michael

 

[Mick c]

I have a 1982 46 HP with the 8-92's. Top speed is 27 KTS but not getting full RPM either due to a less than honest bottom diver or it seems port side not getting full throttle or both. Was told it was 30KT boat new. Cruise is 20KTS at 1750-1800 RPM. A similar HP modern engine would give same top end but higher cruise since they can run higher RPM's than a DD at cruise. I would guess a 23-24KT cruise which IMO is plenty fast. If serious fishing I could see the need for higher HP and speeds. Otherwise we are quite happy at 20KTS. Owners preference and needs are the deciding factors.

Hi, we actually have no intention of using the boat for fishing and it will just be cruising the harbour and maybe an occasional coastal run. It just the rev head I us that we would like to achieve the 30 knots but it’s not that important but if we are searching for new engines then we might as well use that as our benchmark.regards Mick

 

[Mick c]

The boat is in place at our Workshop in Wesern Sydney where we are fortunate enough to have plenty of room and all the facility’s we need to carry out the project. It’s just about time and money now.We have started to strip out the boat and I must say it is a bigger job than I imagined but we have enjoyed every moment of it. Hopefully when we can both get a full weekend we will remove the engines and start refreshing the engine bay and the rest of the hull.Keep you posted as we go. Thanks for showing interest and helping out with your advice. Regards Mick C

 

[Mick c]

More photos

 

[krush]

The HP will do right about 30knots in good shape....just look at this one: https://www.samsmarine.com/forums/showthread.php?10349-29.1-knots-on-the-bay

It is a 1983 46C HP model with 650 HP 8V92s. When it was new it would hit 33kt on the Northstar. The pic was taken by my friend on his 1985 45C, after he took pics of me, we took pics of his boat. Dave

And other cruise pics: https://www.samsmarine.com/forums/s...ay-was-one-of-those-perfect-days-on-the-water

 

[Mick c]

The HP will do right about 30knots in good shape....just look at this one: https://www.samsmarine.com/forums/showthread.php?10349-29.1-knots-on-the-bayAnd other cruise pics: https://www.samsmarine.com/forums/s...ay-was-one-of-those-perfect-days-on-the-water

I read somewhere that the non HP hull like ours gets into trouble at around 26 knots? Have you heard what mods they do I prove the handling? M

 

[Boatsb]

Remove 3 foot of keel aft and knife the front of it.

 

[madhatter1]

The thread krush posted link to is the one I own. Right now I am only getting 2150 RPM on port and 2275 on starboard while reaching 27kts. So when we fix whatever is holding back port I should reach the 29 kts Dave was getting. We don’t carry a bunch of junk on the boat so not sure how it is 4 kts off of what it reached new. Maybe that run was with empty water, holding, and aux tanks.

Anyway if you go in the 600-700HP range you get an idea on performance. As for modification to the hull on the HP the only one I am aware of is the “ cut down keel”. Don’t know if hull was built this way or modified after.

 

[jim rosenthal]

I have a 45 Series 2 convertibles with Cummins QSM11 660hp 2" shaft that I purchased in New Orleans area 4 years ago. At sea trial in Lake Pontchartrain, we reached 30 knot@2,350 rpm. After taking the boat to Rep. of Panama, I found it over-propped and could only get 26 knot@2,200 rpm (for some [FONT=arial, sans-serif]reason it happens with many boats when they are moved to Rep. of Panama, maybe due to high humidity, I do not know).
I have now gone from 28x32 prop to 28x30 and to 28x28 prop and get 26 knot@2,350rpm and ithe engines are also right on the fuel curve, I have also added a dinghy.[/FONT]

We have another forum member, Captain Coop, with a similar boat, with M11s. I believe she did 34 kts on her sea trials, and was only up to 94% load, if I remember accurately. The 45 Series 2 hull is faster potentially than the 46HP, but perhaps not quite as sturdy. This is a relative matter as I have never seen a Hatteras yacht which one could describe as fragile, or not sturdy.