NV23 scaled down 10%

[alex2293]

Hi,

I'm still wondering if the HMD19 is the right boat for me. I'm considering the NV23 scaled down 10% in every direction.

It would give a length of 20ft 6in with a beam of 7ft 4in.

I'm not looking for a boat with a lot of creature comfort, but one that can run at displacement speed and low planning speed economically.

A cuddy with seating space and a porta potty.
A short hard top without sides.
2 forward facing seat at the helm.
2 side benches just behind the forward seats.
A cooler.

When scaling down the boat 10% in every direction, does the displacement and ppi reduces by 27%?

Since it is the same hull shape as the NV23, the same speed can be achieved with less power if the displacement is also reduced? A 60hp Tohatsu 4 stroke would be in my budget and troll economically without a kicker.

What is the freeboard of of the NV23?

Thanks a lot.
Alex

[TomW1]

I had to re-read your post several times to understand what type of boat you were looking to build. So you want a boat that can both plane and also run at displacement speeds. The NV23 can do this for you. The problem is selection of a motor. A motor to plane the NV23 down sized to 20' would be a 40-50HP. But you can't maintain displacement speeds for long periods of time with that motor. Short periods like when your trolling fishing, yes, but long term stretch's of continuous running at displacement speed, no. I would recommend a main motor and a kicker motor for displacement speeds. Even in the Great Lakes they use there big motor to get to the Walleye and use there kicker to troll for them, with there +/- 20' boats.

Well I hope that helps you.

Tom

[alex2293]

My question wasn't very clear.

I was considering the HMD19 for its fuel efficiency, huge capacity and great cockpit size with a short hardtop.

However, I plan to use it on the St-Lawrence river where I would might have to play the tide like a sailboat with the HMD19.

The LB22 speed, hp and mpg would be perfect but is it a bit small in terms of displacement and cockpit size due to the motorwell.

I guess that I'm looking for semi-displacement speed to get to the fishing spots a bit faster, come in a bit faster if the weather gets worse or make progress against the tide.

There was a thread about a 1973 22' Pogo lobster boat that looked pretty good. It had 60hp Isuzu diesel engine with a cruise speed of 6 knots and would plane at 10 knots at almost WOT.

I was wondering if the NV23 could operate like the 1973 Pogo. It makes no sense to me to have a 15k outboard to get to the fishing spot in 15 minutes (a few miles off shore at 30mph) to troll for hours at 2mph with a 4k kicker.

Thanks
Alex

[fallguy1000]

I think I'd build her as is..

For a river boat, you'll be happy with her powered anywhere from 50-70. If you are planning offshore use, go to the 70 Yamaha...best in class by weight..

I think it'd be a dream boat for the seaway.

I have a Merc 50hp and I have a trolling plate on it. I drop the plate and it does fine. I have a reserve motor I can troll with, but the 4k kicker won't work. Only at wot for a reserve.

I have enough power to troll forward in the wind with the big engine only.

Props are too small on kickers.

[alex2293]

Building the NV23 would be a nice boat but a bit big for my needs, budget and local lakes and rivers. If I build this boat I would leave it at a marina on a smaller river inlet near the St-Lawrence river. A 20ft would have a lower docking fee and be a bit cheaper overall.

What got me interested in a very slow NV23 is this thread: viewtopic.php?f=8&t=62695&p=482049&hili ... er#p482049

TomW1 said: " PomPom I ran your specs through my calculators using the numbers from the study plans a yamaha 25 and other figures I have. The max speed should you ever need it is 19 mph with the 25. The hull speed is 6,9 mph. The prop recommended was a ss 9,5d x 8p. You would get excellent gas mileage running @2500 - 3500 rpms, you will just have to try each and see which is best. "

Matt Gent seemed to disagree from his experience with his DE25. He suggested that a 25HP on a DE23 could push the boat against the hump at 12-13mph.

So here I am wondering if a NV23 scaled down 10% could used to troll and up to 12mph with a 25HP high thrust.

Not getting on plane is not an issue for me, I'm using a 16ft tiller boat with a 4hp at 5mph right now. An outboard is also more easily replaced than the boat itself if one day I want to go faster ($$$).

Sorry for the confusion in my original question
Alex

[BarraMan]

I am missing something here!

I don’t troll! Never! Period!

However where I fish, people do troll - backwards and forwards, all day, every day. Always in boats with planing hulls and always with the only motor available - the one that puts the boat comfortably on the plane. Hell, my 40 hp 4 stroke Yammie has built in trolling features. My 250 Vmax SHO may also - can’t say I’ve ever looked for it!

[fallguy1000]

I am missing something here!

I don’t troll! Never! Period!

However where I fish, people do troll - backwards and forwards, all day, every day. Always in boats with planing hulls and always with the only motor available - the one that puts the boat comfortably on the plane. Hell, my 40 hp 4 stroke Yammie has built in trolling features. My 250 Vmax SHO may also - can’t say I’ve ever looked for it!

Trolling for walleyes is generally slow, although my friend always trolls for a reaction bite 2-2.5 mph.

I prefer to troll em at 0.9 mph. Or drift fish at 0.4mph. You need a drift bag..

[TomW1]

have redone the specs for a NV23 -10%. Length 19' 10" x 7' 4.25". Displacement about 1900-2000lbs. PPI 350-400. These are from my calculations that I have. I will come up with some speed and prop numbers shortly.

Tom

[TomW1]

Let's go over a couple of things first. As the NV has a monohedron hull so as it reaches planing speed it just continues on with its speed increase. There is no hump to break through that a V shaped hull has. The hump is not there. So any way here are some numbers I have come up with.

The NV23-10% with a 25HP motor will have a top speed of around 20 mph. Cruise around 16-17. At displacement speed around 6.5 mph. With the currents that you say you have, I would recommend a 4 blade prop. of about 9 x 7. A 4 blade gives you better control in those conditions.

Well good luck on your decision.

Tom

[alex2293]

Thank you Tom, that is exactly the boat size, speed, outboard power and information I was looking for.

I have one or two last questions. I'll try to be as clear and concise as possible.

In the NV23 study plans, the displacement is 2500lb and PPI at DWL is 560lb. The NV23 is self-bailing up to what displacement? At least 3500lb from what I understand.

When a boat is self-bailing, is the bilge completely dry? Does it have a bilge pump in case something happens? A drain plug to drain any water from a leaking inspection hatch?

Thanks again, this is amazing to see the amount of support on this forum.
Alex