How fast will a kicker motor push a 21 footer?

[lenpilot]

I have a 21 foot center console offshore (Like a mako) with fuel and gear probably weighs about 3000 or so. I am hoping to go out pretty far at times. I have a 200 suzuki that runs good but I had some fuel flow problems that made me think about adding a kicker. <br /><br />Does anyone have a kicker on a boat like this ? How fast should I expect to go. If I can bring the boat back say 10-30 miles at 7 or more knots, I think it could be a good investment.

 

[JB]

Re: How fast will a kicker motor push a 21 footer?

Howdy, Lenpilot. First of all: If you have ANY doubts about your main powerplant, DON'T go out.<br /><br />A 20 to 30HP kicker, with appropriate prop should give you your 7Kt, but it may not keep sea in a storm (see above advice).<br /><br />Good luck.<br />Red sky at night. . .<br />JB

 

[saltwateranglin]

Re: How fast will a kicker motor push a 21 footer?

What are your fuel flow problems?

 

[lenpilot]

Re: How fast will a kicker motor push a 21 footer?

Thanks JB <br /><br />I have doubts about all motors and all situations. It would have been called Leonard's Law but Murphy beat me to it. I am one of those people who like to have a plan b for everything.<br /><br />I was thinking about a smaller engine, along the lines of a 9.9 - 15 hp. but that probably would not be very much help that far out. I don't plan to go way out too often, but my criterea for this boat was that I want to be able to tow it anywhere and fish places like Islmarada hump (10 miles off the Fl keys), Chesapeake Bay, Gulf of Mexico, and any water that is reasonably calm on good days.<br /><br />Mike,<br /> My fuel flow problem turned out to be a glogged sreeen in the 111 gallon tank (Now I carry a 5 gal reserve tank.) I think it's fixed now. But I had to limp in slowly at dusk with my wife and 2 kids in 2-3 ft seas in the Lower Potomac. As a result of that, I have to fish alone now (they don't like to go any more) Hopefully that will change by next summer.

 

[saltwateranglin]

Re: How fast will a kicker motor push a 21 footer?

If it were me, I would eliminate the screen in the tank and use a good fuel filter/water separator mounted in a easily serviced position. I would hate always wondering if more garbage was floating around the pick up waiting to jam. Since your boat most likely won't accept twins, I would install the kicker for shear purpose of slow trolling and maybe aiding in getting you closer to land where a tow service would not cost quite so much. Joining a towing club like Boat US or Sea Tow would be a good idea also. I used to run all the time with a single 150 for tuna and nothing ever happened but it always bothered me. Now I run twins but still other things can happen. Run with a buddy and a good tow service.

 

[suzukidave]

Re: How fast will a kicker motor push a 21 footer?

Lenpilot, I've seen something that might appeal to you (and the family)-- check and see if your transom would accomodate an old skinny 50 hp Merc or similar beside the 200hp and stick a very low pitch prop on it. Set up for dual steering/controls and keep the little one's leg up most of the time. Seen it done -- works great -- you'll pay about the same for an old 50 as you would for a 20-30hp kicker, and the 50 should get you home on plane at 15mph if you break down or at fast troll in a sea and can also be used as a trolling motor on a boat that size with the low pitch prop on.

 

[JRJ]

Re: How fast will a kicker motor push a 21 footer?

Suzkidave has an interesting idea. I guess the 50 Merc would have power tilt and that would eliminate one of the things I don't like about my kicker setup. It can get a little shakey messing with the 100# 'lil rascal as the ocean gets sloppy...I'm thinking twins someday.

 

[Wan Zai]

Re: How fast will a kicker motor push a 21 footer?

I hv a 90 hp Mariner [2000] 2-stroke and a 40 hp Selva [1997] 2-stroke. The Selva is from Italy and only weight 54 kg at 2 cylinder 2 carb 450 cc. I use the Mariner as main engine and the Selva as trolling and get home engine. I can get about 13 mph from the Selva on a a 27 footer FRP open deck long boat. I mount the Selva directly to the transom and put a remote control unit and link it to the Mariner for steering.<br /><br />I plan to fix a starter motor to the Selva later. There is no power trim option for the Selva, other wise it would be ideal.<br /><br />Previously, I use a Yamaha 15 hp kicker on a bracket but the sea condition is my area is very rough such that a 15 hp will be very slow and when I run the Mariner at high sea, it is just a matter of time the 15 hp will fall off from the bracket. I also don't feel very safe sitting at the back of the boat at high sea holding the 15 hp tiller handle when I test the setup.

 

[Beernutz]

Re: How fast will a kicker motor push a 21 footer?

I carried a 15hp kicker for a couple of years, but haven't mounted it on my last 2 boats. I never needed it for an emergency, just used it for economical trolling. Also, it seems that a little different sound will attract fish and entice them to attack. I was never really satisfied with that arrangement, though, due to the loss of maneuverability when you get a fish near the boat. I don't know how they know about it, but angry striking fish like to charge a spinning propeller. Tiller control was a nightmare under those circumstances. I got where I'd fire up the main engine when we got a hookup, and shut off the kicker.<br /><br />A kicker will definitely give you more confidence, but as JB points out, sometimes that's not a good thing. Also, I can recall running in choppy seas, looking back and wondering, not if, but when the retractable bracket was going to rip off of the transom. Further, if your main engine has oil injection and your kicker doesn't, you'll have an extra fuel can of pre-mix in the way.<br /><br />You could probably get ten years of Sea Tow for the price of a good kicker. <br /><br />Hope this helps.

 

[saltwateranglin]

Re: How fast will a kicker motor push a 21 footer?

I've got twin 140's on a 23' W/A and I'm lucky if I can get 10-12 kts wide open on one engine much less get on plane. If you guys get 15kts and on plane from a kicker, on a boat that size, maybe I'll go that way next time!

 

[fishthebay]

Re: How fast will a kicker motor push a 21 footer?

I have 2 kickers and both are broke. I have given up and signed up for sea tow at $95.00 a year. Hey, it's better to pay $95.00 bucks and have unlimited tows and fuel drops vs breaking down and swimming in.<br /><br />A thought if you don't want to add the extra weight to your boat.

 

[suzukidave]

Re: How fast will a kicker motor push a 21 footer?

saltwaterangling, maybe it's the way you prop those 140's. I know that an old 50hp Merc will make an old 21' reballo plane in a moderate sea when the 225hp main motor quits and it seems like about 15mph to me. In rough water you'd be fast trolling. I've seen other boats with the same rig. <br /><br />Up here towing is not always an option and it is always a long wait.

 

[saltwateranglin]

Re: How fast will a kicker motor push a 21 footer?

Suzkidave, this rig was rigged by the previous owner who just happened to be a high level engineer for Boeing. The 15x17 stainless, counter rotating props were tested to give optimum performance without exceeding WOT range or toping out before it. Talking with several others with twins over the years , I have found many have great difficulty getting on plane in moderate seas and most tell me of average speeds of 7 to 15 knots. I can't explain why a boat that does over 50 on two engines will only get 10 to 12 knots but I do know there are quite a few of us that can testify to it.

 

[Wan Zai]

Re: How fast will a kicker motor push a 21 footer?

With twin 2-stroke outboard, the pitch of both prop must have been optimize to WOT [5000-5500 RPM]. Once, you lose one engine, the WOT drop below maximum recomended range, maybe 3000 RPM. At this RPM the HP for a 140 hp engine is only about 84 horse. Lower than my 90 hp Mariner at 5500 RPM. In addition, it has to carry the weight of the other 140 horse engine and a heavy boat that can handle twin 140 horse.<br /><br />Boat with 280 HP total power may need a kicker in the range of 60-90 HP plus a single 250 HP. It will depend on the weight of the boat. It will probably be better to use a 4-stroke kicker to get the optimum power at lower RPM. 2-stroke optimum power curve is very high up on the RPM curve compare to 4-stroke.<br /><br />With a main and kicker setup, I hv an optimize setting with 90 hp main engine [17" pitch] and 40 hp kicker [10" pitch] all running at recomended WOT range. Total weight of my boat is only 3200 lb with 2 person on board and 50 gal fuel. I am really playing with power to weight ratio to get a reasonable speed and range. I plan to upgrade to SS prop later mainly to get more range rather than speed.<br /><br />I like this setup for the following advantage :<br /><br />1. If I hit a rock, my kicker is still safe because it is not in the water.<br />2. I still have all the advantage of twin power with separate fuel tank. I'll will install separate batery for the kicker later and currently use rope starter.<br />3. Since my kicker throtle is remote control. I can still steer the boat with throtle, although not as refine but good enough in case of steering failure.<br />4. During very rough water at inlet, storm or rocky cape, I put down the kicker with engine on ready to take over in case the main engine fail.<br />5. During, normal condition, I ran only single main engine at very economical fuel consumption and get a very good range.

 

[saltwateranglin]

Re: How fast will a kicker motor push a 21 footer?

Sudden Impulse, thanks for shedding some light on the reason for the drastic reduction in horsepower when running one out of two. Makes absolute sense and is the first logical explanation I have heard yet.

 

[Wan Zai]

Re: How fast will a kicker motor push a 21 footer?

You can get back the maximum horsepower if you change to a lower pitch after loosing one engine but I am not sure if it is practical on a high sea.<br /><br />I would'nt wan'na be hanging on a 140 horse lower leg juggling a socket wrench and a wood block during choppy sea.

 

[saltwateranglin]

Re: How fast will a kicker motor push a 21 footer?

Sudden Impulse...you are right about on a high sea but I may just carry a low pitch prop with me if that will help get home quicker in calmer conditions. It's a long ride from 50 mile out at 10 kts or less! I'm sure the stress on the engine would be much less as well.<br /><br />By the way...you sure are coming through loud and clear all the way from Malaysia! Thanks for the info and tips.

 

[letsbarbq]

Re: How fast will a kicker motor push a 21 footer?

lenpilot,<br />can you tell me what you did? i have a 20 foot wellcraft steplift and got a 150 hp. and i go off shore in the gulf here in texas. i got a bracket and was loking for a kicker motor ...and i dont know what hp to get?... i like the sound of putting a 30 or 40 hp on the transom.... did you do it.. and how is it working...<br /><br />please let me know.

 

[DJ]

Re: How fast will a kicker motor push a 21 footer?

If you have room on the transom, go with a 25-40 kicker four stroke. These are available with trim and tilt now. Don't expect one to plane the baot though. I doubt a fifty would either.<br /><br />Your Suzy is oil injected so you can run off the same tank.<br /><br />Good idea about the fuel/water seperator. These have "spin on" filters. Carry a couple extras until you get the trash out of that tank.

 

[letsbarbq]

Re: How fast will a kicker motor push a 21 footer?

hey djohn19,