will a 3.5 push my 15 ft fiberglass trihull up a river pretty good?

[squirrel30668]

So i have a 15 ft fiberglass trihull and a 1984 dt3.5 suzuki on it. Haven't brought it to the water yet and wanted to know if it would be enough to get me where i needed to go. Speed is not a issue. Just getting from point a to point b and then back to a. the rivers here arent that fast moving and was wondering if the 3.5 would work for me

 

[shrew]

Re: will a 3.5 push my 15 ft fiberglass trihull up a river pretty good?

What is "Pretty Good"? My 2 HP Honda pushes my 8ft. inflatable dinghy about 4-5 knots with 2 people in it. It depends on how fast the current on the river is. If the 3.5 pushes your boat at 5 kts and the river has a 3 kt current, you'll be making a 2 kt headway speed up river. Is that a pretty good speed?

 

[crabby captain john]

Re: will a 3.5 push my 15 ft fiberglass trihull up a river pretty good?

The capacity plate will give you a minimum recommended HP. That should give you an idea how low you are. A tri-hull has a little more resistance in the water than a mono-hull. When you launch head UP stream 1st as you don't want to go down and find you will not get back to the launch until much later than you like. Rain {or snow melt if you live in a cold area} will add to the speed of the current. Depending on the river and your location on it that process could be days.

 

[Ned L]

Re: will a 3.5 push my 15 ft fiberglass trihull up a river pretty good?

As has been said, as long as there isn't a good current It will do just fine. YEARS ago I had to use a 2hp on the back of a 12' john boat as a "pusher tug" to move a 24' diesel inboard about 5 miles, it was slow going as the 2hp was old & getting tired & hit only about 2/3' throttle, but we got there.

 

[squirrel30668]

Re: will a 3.5 push my 15 ft fiberglass trihull up a river pretty good?

Ok where do i find the capacity plate?

 

[Home Cookin']

Re: will a 3.5 push my 15 ft fiberglass trihull up a river pretty good?

I'd say "no" and it would be dangerous to try without a friend in a properly rigged boat nearby. And if you boat where there's other traffic, you are the old man in a goofy hat going 40 in the left lane of the interstate, blinker on the whole time. Don't be that guy.

 

[blackhawk180]

Re: will a 3.5 push my 15 ft fiberglass trihull up a river pretty good?

I'm going NO on the "up a river petty good" part. Even if the river is only going 1 mph with no wind (we regularly get 5+ mph currents where I live near the Columbia river and it's dam systems). A 3.5 hp motor is a kicker at best and MAYBE top out at 4-5 mph. Kayaks will be passing you like the old man in the fast lane.

 

[JimS123]

Re: will a 3.5 push my 15 ft fiberglass trihull up a river pretty good?

We used to run a 3.5 on a 14' tinny and it was marginal at best. Change the hull to glass and a trihull besides and the answer isnt no, but heck no.

Even more importantly, before you do take the boat out, you would be well advised to buy and read a boating safety book and learn all about capacity plates and all the other important info.

 

[smokeonthewater]

Re: will a 3.5 push my 15 ft fiberglass trihull up a river pretty good?

I'm gonna estimate 2-3 mph.... I can say that my 1.5 on my buddy's 8' plastic bass boat ( that I can lift over my head) has NO business on a river and I think you will be slower yet.

I'd say 7.5 hp MINIMUM and you'd need to run along the shore, not out in the middle and run upstream first and downstream to come home.

 

[rallyart]

Re: will a 3.5 push my 15 ft fiberglass trihull up a river pretty good?

No.

 

[zimm17]

Re: will a 3.5 push my 15 ft fiberglass trihull up a river pretty good?

Dude I had a 20hp on my 14' inflatable- which only needs 1/2 the power a fiberglass boat does. I think my shop-vac has 3.5hp. Bring some oars.

 

[Triangleboater]

Re: will a 3.5 push my 15 ft fiberglass trihull up a river pretty good?

So I run a 1961 3hp rude on my 16 ft canoe that weights in at a whopping 85pounds and then my wife, some beer and myself... We hit maybe 7mph....We only do rivers and salt water because if the engine quits on us...it's a canoe we can paddle. but your boat....don't think I would try it.

 

[kfa4303]

Re: will a 3.5 push my 15 ft fiberglass trihull up a river pretty good?

I doubt the 3.4 will be enough. I would use at least a 5hp motor, if not 10hp. Currents can be stronger than they seem and work against you while underway. As a result, you'll need power to overcome it. I used a little 3hp on my 14' tinny it was just barely enough to fight against the current. Better to have the power and not need it, than to need it and not have it.

 

[IraRat]

Re: will a 3.5 push my 15 ft fiberglass trihull up a river pretty good?

Dude I had a 20hp on my 14' inflatable- which only needs 1/2 the power a fiberglass boat does. I think my shop-vac has 3.5hp. Bring some oars.

Aren't inflatables real funky with strong winds?

I would think that lengths being equal, you would need MORE power with an inflatable.

 

[rallyart]

Re: will a 3.5 push my 15 ft fiberglass trihull up a river pretty good?

Inflatables are the same as similar sized tin or glass boats in the wind because the wind is pushing on the same area. The length or a 14' boat is 14', even if you measure it from one end to the other on two different boats. You need much LESS power to move a lighter hull than a heavier hull which is why inflatables normally use less power. You may be mistaking the fact that inflatables are normally rated for higher power than a glass boat of similar size with a need for that power. It is instead related to the greater load capacity of the inflatable due to its design. A 6hp on a good 14' inflatable would get it planing but it would be rated at 30hp or more and run 50 MPH with that.

 

[NYBo]

Re: will a 3.5 push my 15 ft fiberglass trihull up a river pretty good?

I used a 3.5 on my Coleman Crawdad (11' 2" plastic hull, flat bottom, maybe 100#). With two aboard, trolling motor at the bow with Group 27 battery, a cooler, and fishing gear, we zipped along pretty well. Not planing, for sure. Your hull speed is greater because of the greater length, and you might come close to it if you keep the load light. The only way to tell is to try it out. Do you have a lake or pond nearby so you don't have to contend with current?