2001 340 Sundancer purchase decision....

Those performance numbers don't sound right. 20mph at 4000 rpm sounds way too low. And you said a minute to get on plane with 3 people. I hope you don't mean 60 seconds. You should be on plane in 10 seconds max. My boat is the same basic hull. I have carbed 7.4 litre engines, but everyone's earlier posts said that the 6.2s are very close in power. I am on plane in no more than 10 seconds and here is what my dash looks like at cruise speed of a bit over 31 mph:

DSC_0053.jpg


DSC_2358.jpg
 
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Creekwood said:
Those performance numbers don't sound right. 20mph at 4000 rpm sounds way too low. And you said a minute to get on plane with 3 people. I hope you don't mean 60 seconds. You should be on plane in 10 seconds max. My boat is the same basic hull. I have carbed 7.4 litre engines, but everyone's earlier posts said that the 6.2s are very close in power. I am on plane in no more than 10 seconds and here is what my dash looks like at cruise speed of 30mph:

DSC_0053.jpg
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thanks. When I said 'a minute to plane' that was not literal. We started off slowly and then jumped up on plane. I am not sure of the actual time to plane from a dead stop. The broker said the boat has not had the bottom cleaned in a long time. Not sure how much a dirty bottom can affect overall performance. The 20 mph at 4,000 rpm was not verified with my phone GPS. It was read on the Raytheon multi function gauge on the dash. I am not sure how accurate it is. From what I have read 3,800 - 4,000 rpms for planing speed for the 6.2 engines is common. These engines are designed to rev higher than the big block engines to make the same power. I am a little surprised to hear your boat can run at 30 mph at 3500 rpms. I was under the impression that top speed for thes boats was around 30 mph for V drives. Did you install larger trim tabs by chance? I have read this can help planing performance.
 
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No, top speed is just under 40mph with vdrives and the 7.4s. The two pictures I am showing are taken seconds apart so that is the RPM and speed.

Its possible that the hull is really dirty, but it should have antifouling and in fresh water you don't get the same kind of fouling as in salt. Maybe David on Saint Max will post back with his speed at that RPM. That will give you some exact comparison to tell the surveyor.
 
I am by no means an expert - but will share my experience. When I recently went through survey process, the Cummins dealer doing the engine survey would not do the survey unless the bottom was cleaned first. His opinion was it could have too much impact on performance if it wasn't clean.
 
My Raytheon speedo function is not accurate. It shows a slower speed than GPS.

It gets less accurate the faster I go and reads 9 mph slower than GPS at full throttle.

I believe The speedo gets it's signal from a little paddlewheel, In a thru hull, on the bottom of the boat. I should probably inspect and clean it… just haven't got around to messing with it.

You definitely need to verify speed with GPS.
 
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Creekwood said:
Those performance numbers don't sound right. 20mph at 4000 rpm sounds way too low. And you said a minute to get on plane with 3 people. I hope you don't mean 60 seconds. You should be on plane in 10 seconds max. My boat is the same basic hull. I have carbed 7.4 litre engines, but everyone's earlier posts said that the 6.2s are very close in power. I am on plane in no more than 10 seconds and here is what my dash looks like at cruise speed of a bit over 31 mph:
Click to expand...

thanks again for your input. one thing that can contribute to the better performance of your boat vs. the one i am looking at is the weight difference. According to NADA your boat weighs 11,200 lbs. dry and this boat weighs 13,000 lbs. dry. 1,800 lbs is a significant amount.

cliff
 
just spoke to the mechanic. All cylinders on both engines had compression of 175 or higher. Engines seem to be in good health. Mechanic ran out of time today so he is going to check the compression on the generator tommorrow as well as other items in the bilge such as bilge pumps.

so far so good.

cliff
 
If your guy is doing a compression on gen have him put in new plugs it will save you a lot of time later on they are tought to get to. The weight of 13200 does not include gen total dry is 13500. I have 7.4 mpi and top speed is around 30 with 17 x 15 pitch props.
 
The 320 Sundancer with small blocks likes to run around 3700 to 3800 rpms on plane. I would expect the speed to be mid 20's mph on GPS. Sounds like you have a nice boat.
 
vandal said:
If your guy is doing a compression on gen have him put in new plugs it will save you a lot of time later on they are tought to get to. The weight of 13200 does not include gen total dry is 13500. I have 7.4 mpi and top speed is around 30 with 17 x 15 pitch props.
Click to expand...

thanks. the owner said he had the engines tuned up in march of this year which included new plugs. I asked the mechanic to verify this and if he felt new plugs were needed to go ahead and put new ones in. he said the engine plugs looked new. i did ask him to go ahead and put new plugs in the genny tommorrow, regardless of what they look like. I have read many times over that a genny needs fresh plugs to stay in top condition. your top speed of around 30 is what i have read as being normal for these boats. now that i think about it i don't remember if the Raytheon speedo was reading in knots or mph. i think 20 knots is around 23 mph, so that may be about what i would expect at around 3,800 - 4,000 rpms.

i did not realize the dry weights stated in NADA do not include the genny. Thanks for that.

cliff
 
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Interesting. I had no idea mine was a go-fast boat. I need to get me some gold chains and some more chest hair. I am surprised that the 1800 lbs makes that much difference. I think mine has 17x17 props and my wot is about 4200 and 38 or 39 mph. I think the stern drive versions run well over 45.

Anyway don't be intimidated by the size. It won't take long and you will be comfortable with how it behaves and will find it far easier to manoeuvre around the dock. Twin vDrives are a dream compared to single i/Os. My first summer I was a bit nervous but by fall was very comfortable. The next spring it was totally comfortable and now i don't really even think about it. It's a great handling boat.
 
Creekwood said:
Anyway don't be intimidated by the size. It won't take long and you will be comfortable with how it behaves and will find it far easier to manoeuvre around the dock. Twin vDrives are a dream compared to single i/Os. My first summer I was a bit nervous but by fall was very comfortable. The next spring it was totally comfortable and now i don't really even think about it. It's a great handling boat.
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Thanks. oddly enough i really did not feel 'intimidated' by the size, just respectful. i feel sure i can and will learn to handle the boat with some practice, but i did not want to start bumping and banging into things until i get some practice time and some lessons from a more experienced captain. i plan to reach out to our local power squadron to see if i can hire someone to give me lessons. there is very little activity on the lake and at marinas this time of year so the timing is good for getting in some maneuvering practice without a lot of concern about other boats in the area. by watching the broker handle the boat around the dock i can already tell the advantages of twin engines vs. a single outdrive when docking. the boat is very responsive to subtle commands from the helm.

cliff
 
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Creekwood said:
Interesting. I had no idea mine was a go-fast boat. I need to get me some gold chains and some more chest hair.
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LOL, that's funny and so true:) The boat slipped next to ours is a 50' go fast cigarette type made years ago by Wellcraft. It's exhaust's diameter is bigger than a lot of dinner plates, not to mention the noise :) And just to complete the very classy "ensemble" it comes complete with Speedo swimwear:)


Sent from my iPad using Tapatalk
 
The Ray Tri Data is a paddle wheel. Not accurate. You need GPS data. I too get 40 knots at WOT same as the 7.4 above.


IIRC, SR used 17x17 on 4 blades and 16x16 on 3 blades. The only difference between the two is at the slip or close quarter maneuvering. Properly tuned both will perform similarly in the "real!" Water.
 
I am sure these are exciting times! Having just bought our boat this past May, I did learn one thing that I will share with you. We had an excellent surveyor that brought in a certified mercruiser tech to do compression checks, etc. One thing that was not checked that just cost me was the oil pan. In the future I will always run my hand down under and all over the oil pan. If I cannot get to it, a mirror or phone pic would suffice. Mine had been patched by the original owner, not the PO. It was a low hour boat and general consensus was that it sat for long periods of time and any moisture in the oil found the low point in the pan and created rust. Just my $0.02. Have fun and best of luck!

Bennett
 
dpmulvey said:
The Ray Tri Data is a paddle wheel. Not accurate. You need GPS data. I too get 40 knots at WOT same as the 7.4 above.


IIRC, SR used 17x17 on 4 blades and 16x16 on 3 blades. The only difference between the two is at the slip or close quarter maneuvering. Properly tuned both will perform similarly in the "real!" Water.
Click to expand...

Thanks David. According to the spec sheet the original props on the 2001 model 6.2 boats are 17 x 19 with 3 blades. unless the PO changed them out they should still be on the boat. will check them out when we pull the boat for the survey.

i have read your archived posts about enlarging the trim tabs to get better planing performance. Once we get settled in with the new boat i may ask you for some details and guidance on doing the same for my boat.

sounds like the Raytheon Tri Data gauge will be good for water depth and water temperature but not so much for speed. The original Raytheon GPS/Chartplotter on the boat works but i don't think it had a map card installed. Can these maps still be found?

cliff
 
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bbwhitejr said:
I am sure these are exciting times! Having just bought our boat this past May, I did learn one thing that I will share with you. We had an excellent surveyor that brought in a certified mercruiser tech to do compression checks, etc. One thing that was not checked that just cost me was the oil pan. In the future I will always run my hand down under and all over the oil pan. If I cannot get to it, a mirror or phone pic would suffice. Mine had been patched by the original owner, not the PO. It was a low hour boat and general consensus was that it sat for long periods of time and any moisture in the oil found the low point in the pan and created rust. Just my $0.02. Have fun and best of luck!

Bennett
Click to expand...

thanks for the heads up on the oil pans Bennett. i'll be sure to check them out. This boat has not sat unused for long periods of time, but it is still good to check things like this out.

cliff
 
I don't have anything to add but best wishes. I want to thank Creekwood for the pic! I rarely run mine up at that RPM. I like to stay around 3000 sometimes 3200. I cruise around 20K at 3000 and 23K at 3200. Up where Creekwood was at I would be around 27K which should be around 31mph so I think I match too.

Enjoy the boat she is great.
 
Cliff, I can help you with handling twins if you want. I'm sure Jim will help out also. Just get ahold of me and Ill come running. Haha I have a slip at Midway marina and Knot Tide Down is there right now. Let me know.
 
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