Moving upstream in a displacement boat?

[Biker B.O.B.]

Thinking about my next build...

My wife has finally spoken, and she would like to poke along and look at wildlife and scenery. I'm ok with the relaxed pace, but in order to not limit us to a few, small, house lined lakes, I have to consider travel along some local rivers too. I like the idea of a displacement hull for two reasons, powered by an electric motor it will be quiet and relaxing; plus, if I select carefully, it can serve double duty as a sailboat.

But one thing concerns me. Quick calculations show shat a lazy float downriver for 30 minutes could result in one-and-a-half hours or more trying to get back to the ramp. Or vice-versa, an hour-and-a-half beating upstream for a half hour float. Am I off somewhere? I'm not real keen on a one-way downriver float; we can simply use the kayaks for that. I might be forced into a planing boat with more power to get back up river; noiser, but I'd like to get input from other folks.

Thanks

[Cracker Larry]

How fast is the current? Many times in a sailboat I've had to throw out the anchor and wait for the tide to change. It ain't likely to ever change in a river It's a lot easier to slow down a planing boat than it is to speed up a displacement boat.

[Biker B.O.B.]

The official data for the Withlacooche River (FL) says 2-3 mph, and on that river I'm far enough upstream that tides won't matter. I've seen the Weeki Wachee River flowing (what I would guess to be) much faster with an outgoing tide. It was quite a strugle in the little 10' kayaks to go upstream, but we managed.

Oh, and I based my example on a 3 mph current and 4 mph hull speed.

[rudar]

Isn't the standard formula for most displacement hulls that V=1.4* sqrt(WL)? (OK, if I recall, that's in knots rather than mph, but close enough).

So if you're calculating a 4kt displacement speed, that gives me an 8.16 foot waterline length. That's a pretty small boat.

If you want to get back upstream in the same time you floated down, you'd need your speed to be twice the current, so at 3kts current, you'd want a 6kt hull speed, which would require an 18.37 foot waterline length.

What boat were you looking at? I'd guess it would be somewhere between the two...

[Biker B.O.B.]

I don't have to move upstream as quickly as I float downstream, but upstream at an effective 1 mph doesn't quite do it for me.

I was looking at a number of different boats; the V12, FL14, OT16, and other similar small boats. I like the quiet nature of the displacement hulls, and the ability to row as a back-up or option. In my research, I found a number of references the the FL14 running about 4 mph with a 40 lb thrust trolling motor or low hp outboard. A 5 hp outboard would get you up to about 6 mph; not really worth it (I'll go with a planing hull first).

A small planing hull (FS12 or GV11) with an outboard might be the better option; but I don't expect it to be so quiet when I'm poking around with the trolling motor. Plus rowing won't be so easy, and I'll have the weight of both the trolling motor battery and the outboard.

I've read that longer skinnier dispacement hulls will move faster, and was looking for someone with experience to tell me how much (or how little) faster it is. Something like the OT16 or SG15.

[Evan_Gatehouse]

Unless you really want to take your time, get a planing hull. The longer hulls CAN be faster but only if you put more power into them. I had a 16' skinny sea kayak and could cruise all day at 3 knots, 1/2 hour at 4 knots, and about 100 yards at 6 knots

Our GV10 dinghy actually rows quite well (transom out of the water) with me rowing (200#), wife on back seat (170#) and kid on bow seat (75#). It helps to have 8' spoon type oars.

At displacement speeds any noise level difference between different hulls with a trolling motor will not be noticable

[Cracker Larry]

I've been in those rivers, got ya now . That's a pretty place 6 or 7 mph would give you an upriver speed of about 3. If that isn't fast enough you'll probably want a planing hull. You mention quiet, but the new 4 stroke outboards are so quiet that at idle you can't hardly hear them run. The cooling water splash is the loudest thing about them.

[gstanfield]

My FL14 will run about 4.2mph with a 40lb thrust electric if I trim it out right by using a tiller extension or by placing some weigh all the way forward. The Platte river by me has a surface speed of about 3.6-4.0 mph so at best I can make a few feet a minute upstream which essentially means I don't go upstream

As said already though, it depends on how big of a hurry you're in as well as what your river is doing

[Biker B.O.B.]

Unless you really want to take your time, get a planing hull. The longer hulls CAN be faster but only if you put more power into them. I had a 16' skinny sea kayak and could cruise all day at 3 knots, 1/2 hour at 4 knots, and about 100 yards at 6 knots

Our GV10 dinghy actually rows quite well (transom out of the water) with me rowing (200#), wife on back seat (170#) and kid on bow seat (75#). It helps to have 8' spoon type oars.

At displacement speeds any noise level difference between different hulls with a trolling motor will not be noticable

Thanks, Evan. That is a lot of the information I was looking for. Of the planing hulls, I was more interested in the GV11; is it that different than the GV10?

I've been in those rivers, got ya now . That's a pretty place 6 or 7 mph would give you an upriver speed of about 3. If that isn't fast enough you'll probably want a planing hull. You mention quiet, but the new 4 stroke outboards are so quiet that at idle you can't hardly hear them run. The cooling water splash is the loudest thing about them.

I guess I've never had the priveledge of hearing one of the new 4 strokes.

My FL14 will run about 4.2mph with a 40lb thrust electric if I trim it out right by using a tiller extension or by placing some weigh all the way forward. The Platte river by me has a surface speed of about 3.6-4.0 mph so at best I can make a few feet a minute upstream which essentially means I don't go upstream

As said already though, it depends on how big of a hurry you're in as well as what your river is doing

George, your FL is one that I found while researching, and where I got the information about the speed of the FL with 40 lb thrust.

[Justin Pipkorn]

Here's a picture of about the max potential for the Otter/Lissa. 6.4 K GPS in flat water, two in the boat, 2 HP Honda at full throttle, weight centralized in boat. The narrow displacement hull designed for rowing tends to bury the stern when powered. Boat worked great at barely half throttle and almost as fast. The Honda weighs only 28 pounds. Hard to match that with electric OB and battery.



More pictures at:

http://gallery.bateau2.com/thumbnails.php?album=1197

The boat rows like a dream and with 2 rowing, it really trucks. I haven't measured the speed rowing yet. The first time we rowed the boat, we found ourselves rowing into about 15+ K wind and waves beginning to form. Rowing was more of a chore but we felt under full control.

We are just starting to sail the boat and it sails well.

We also have kayaks which would be my choice for bird watching. Problem with rowing while birdwatching is that you're looking backwards and with the oars extended, the boat is about 14 feet wide, tough in some narrow waterways. Just a thought of the moment...for birdwatching, I'd just take a long double paddle or two paddles and move canoe style, then row or motor home.