Re: 46 Convertible refit begins
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.
Re: 46 Convertible refit begins
Quote:
Originally Posted by
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/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
Re: 46 Convertible refit begins
Quote:
Originally Posted by
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.
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
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Re: 46 Convertible refit begins
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
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Re: 46 Convertible refit begins
Re: 46 Convertible refit begins
The HP will do right about 30knots in good shape....just look at this one: https://www.samsmarine.com/forums/sh...ots-on-the-bay
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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/sh...s-on-the-water
Re: 46 Convertible refit begins
Quote:
Originally Posted by
krush
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
Re: 46 Convertible refit begins
Remove 3 foot of keel aft and knife the front of it.
Re: 46 Convertible refit begins
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.
Re: 46 Convertible refit begins
Quote:
Originally Posted by
Pearl Island
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 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.
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.