What does S/D at 8kts look like?

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No video... but my 40 with a 34 WLL throws a big enough wake at 6.5 knots that slowing down a bit is required to not upset marina dwellers.

The WLL is what determines speed and wake.
 
No video but I can tell you that any SD boat over 40' is bow level at 8 knots.
 
Couple pics of 56’ waterline x 16.5 beam. 61 tons disp. at 8 knots 6 gph and 10 kts. About 3 times the gph F0DB83B6-44E6-4487-8F6C-4661CA70C3CC.jpg

4B940FB1-6EAB-4201-A644-753442063730.jpg
 
Our boat is variously described as full and semi-displacement. The hull is round and deep with no hard chines, but it flattens a bit toward the stern. (Drawing on the left is amidship and on the right is basically the transom.) The video is us arriving in Chattanooga as we completed the northern half of the Loop. We’re running at hull speed the first 40 second or so of the video, if that’s helpful.

 

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You can watch Tony Flemmings great videos on You Tube. Well worth checking out.

John T
 
psneeld said:
No video... but my 40 with a 34 WLL throws a big enough wake at 6.5 knots that slowing down a bit is required to not upset marina dwellers.

The WLL is what determines speed and wake.
Click to expand...

ksanders said:
No video but I can tell you that any SD boat over 40' is bow level at 8 knots.
Click to expand...

FWT said:
What is it you are trying to see? Wake? Or what life is like at 8 knots?
Click to expand...

Hi, I was thinking wake. But, now that you mention it, what is life like?

This thread could be dead real soon or it could get interesting.

It seems like 8 knots is a good speed for a lot of boats, even a Fleming
 
How a boat behaves at 8 kts will depend a lot on its length. For my 38 footer (33.5 waterline), 8 kts is plowing water, making a big wake, etc. 6.5 or a hair more is a much better speed for slow cruise. A good SD hull may be able to go a little faster before hitting the wall (mine is a planing hull), but not necessarily.
 
phillippeterson said:
It seems like 8 knots is a good speed for a lot of boats, even a Fleming
Click to expand...

I'm with psneed. If you're not planing, it's all about WLL.

8 knots is a great speed for a 64' LWL boat.
 
Nomad Willy said:
Trawlercap,
Your boat is FD.
Extremely over driven in top pic.

Ask Codger2 for a picture of his 34 Halvorsen at 8.5 knots.
Click to expand...

Yes 10 knots is top end for that boat.
 
If someone will lend me a Fleming for a few months I'll take all the video you want.

Here's our CHB 41's wake at about 8kts
 

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Sorry no video

but two photo of our Long-Cours 62 at 11.6 kts
32T, 60' Lwl, 16'4" beam, 14'8" beam at wl
 

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phillippeterson said:
Hi, I was thinking wake. But, now that you mention it, what is life like?

This thread could be dead real soon or it could get interesting.

It seems like 8 knots is a good speed for a lot of boats, even a Fleming
Click to expand...

Because I have a Helmsman 38 on order, as you might imagine I have collected some clip links as I shopped. The one below shows life at 7 knots under the eye of a training captain. At one point one can see the 7 knot speed on the chart plotter. At this speed one has time to think, assess, react.


Below are a few promo videos that appear to be filmed at 7-8 knots.



This is a smaller boat than what you are asking about but perhaps it might be helpful.
 
A screenshot. GB 46, 44'dwl. 12kts. CAT 3208 x 2, 2083rpm. 16.8gph total
 

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Steve1.0 said:
A screenshot. GB 46, 44'dwl. 12kts. CAT 3208 x 2, 2083rpm. 16.8gph total
Click to expand...


That looks almost like a planing wake to me.

For comparison, the pictures below show my boat's wake at 5.5, 6.5, and 17 kts.
 

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rslifkin At 12kts it is almost planing. I think I was surfing a bit in that shot. It's a screen shot taken from a video clip.

I don't know how to post videos to the forum.
 
H38E Video

FWT said:
Because I have a Helmsman 38 on order, as you might imagine I have collected some clip links as I shopped. The one below shows life at 7 knots under the eye of a training captain. At one point one can see the 7 knot speed on the chart plotter. At this speed one has time to think, assess, react.

Nice looking H38E videos, I like the one filmed in San Diego, looks a little familiar.

John T. - N4050, N4061, N3522, H38E former owner

Marshall Marine Sandpiper - current owner
Click to expand...
 
Someone above wanted to see a Fleming’s wake…big boat and big wake. (Repositioning so short run)
 

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N4061 said:
FWT said:
Because I have a Helmsman 38 on order, as you might imagine I have collected some clip links as I shopped. The one below shows life at 7 knots under the eye of a training captain. At one point one can see the 7 knot speed on the chart plotter. At this speed one has time to think, assess, react.

Nice looking H38E videos, I like the one filmed in San Diego, looks a little familiar.

John T. - N4050, N4061, N3522, H38E former owner

Marshall Marine Sandpiper - current owner
Click to expand...

LOL. I know John. It was an oversight on my part not to cite the attribution. Its a nice video of a great boat. Miss it?
Click to expand...
 
bowball said:
Someone above wanted to see a Fleming’s wake…big boat and big wake. (Repositioning so short run)
Click to expand...

It's like a grownup version of double tubing! What size Fleming is that?
 
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rslifkin said:
That looks almost like a planing wake to me.

For comparison, the pictures below show my boat's wake at 5.5, 6.5, and 17 kts.
Click to expand...

Eric said "It's amazing how similar Willys wake at 6 knots looks almost like rslifkin's much bigger boat.His pic is in post #17 above ctr. Our wake from Willy looks like 18hp made it ..... and it did.
 
Nomad Willy said:
Eric said "It's amazing how similar Willys wake at 6 knots looks almost like rslifkin's much bigger boat.His pic is in post #17 above ctr. Our wake from Willy looks like 18hp made it ..... and it did.
Click to expand...

Ballparking it off a prop curve calculation, at standard slow cruise of 1300 rpm (gives 6.5 - 6.8 kts in flat water depending on fuel load), it takes about 30 - 35 hp to push my boat. Not terrible considering the flat transom and significant extra weight compared to Willy (plus likely more wetted surface being a bigger boat). The wake isn't terribly big at that speed, but there is turbulence from the transom. As we burn off fuel, the stern comes up, so less transom drag. Speed increases and the wake gets a bit smaller.
 
Photo of the wake of one of our former boat .
Photo taken at the hull speed limit , around 11.6 kts
very curious design of the bottom but nice blue wake
Twin Perkins 185 hp
 

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Because I have a Helmsman 38 on order, as you might imagine I have collected some clip links as I shopped. The one below shows life at 7 knots under the eye of a training captain. At one point one can see the 7 knot speed on the chart plotter. At this speed one has time to think, assess, react. - FWT

I know my hearing is getting bad but I would swear I heard the training capt suggest they plot their course in the morning using paper charts.
 
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