Thread subject: Whaler Central - Boston Whaler Boat Information and Photos :: musing on kicker motors on my Montauk
Posted by Fishmore on 09/28/09 - 10:41 PM
#1
I am not sure why I am writing this perhaps it is to get some input or perhaps it is just to get it out of my head. I am having a hard time deciding what to do right now about what kicker motor to use, Let me share my story...
This year I decided to get a kicker motor for my boat and my initial though was to put on a 55lb thrust electric motor so that I could troll for trout and use it to correct my drift, Then I decided that the battery did not last long enough, it was rather useless for the ocean and an electric motor with 5 fixed speeds was just not getting the boat to the correct speeds I wanted in fresh water. So first I thought of going to trade up to a variable speed more powerful electric motor and then I realized that price wise and weight wise I could probably run a gas motor.
So I started looking at gas motors and I tested a bunch of different motors some I had and some I borrowed. I tested a 3hp two cylinder two stroke 30lbs, a 5hp single cylinder 4-stroke 55lbs, a 6hp single cylinder four stroke 62lbs and a 7.5hp two cylinder 4 stroke 73lbs.
I liked the low weight of the 3hp but I did not like having to premix fuel and carry an extra tank for it.
The 5 and 6hp motors were ok.
The 7.5 hp did not weigh much more than th 5 and 6 and it went much faster. I thought my problem was solved until recently when drifting on the ocean I had a couple of waves come over the transom due to the added weight of the 7.5hp motor. Now of course being a Whaler when the wave came over the transom I just fired up the main motor and pulled the plug and drained the water out then went back on my drift. Not much of a hassle but still not exactly what i want to do frequently,
So I started back at begining and looked at weights of electrics (hard to determine but I used the shipping weight) and compared those weights to the weights of gas motors. My research showed that an electric motor weighs about 1lb for every 1lb of thrust (plus 50lbs per battery) and a gas four stroke weighs about 10lbs per max hp design. For example a 55lb thrust electric motor weighs approximatly 55 lbs and a 6 hp weighs about 60lbs ( for mercury, tohatsu and nissan the 6hp is the same size engine as the 4 and 5 hp). So that means to me that the gas motor with it's substantially better power to weight ratio is a better motor for my needs. (okay so I got that off my chest and am ready to move to my next decision).
So then I consolidated my likes / dislikes i decided that the ideal motor would weighs as close to 30lbs as possible, move the boat up to at least 4-5 mph and needs to be able to run in fresh or salt water.
So after looking at all available motors I am considering the Mercury/Tohatsu/Nissan 3.5hp motor which weighs about 37lbs (about half as much as my 7.5hp Honda), will run with the same gas as my big motor uses and should still get the boat up to 4-5mph which should keep me out of trouble. Now although I think this is the way to go right now I am not sure i want to lose the speed the bigger motor gives me,
So what would you do?
1. Sell the 3hp 2-stroke and the 7.5hp 4-stroke and go to a lighter 3.5hp four stroke motor.
2. Stick with the 7.5hp heavier/faster motor and risk the occasional wave over the transom.
3. Consider something else?
Posted by Tom W Clark on 09/29/09 - 7:51 AM
#2
3.5 HP is not enough for a Montauk. 6-8 HP is ideal.
A two stroke 6 or 8 HP outboard can weigh as little as 60 pounds. Use a small oil mixing unit (like the Accu-Mix-R) to avoid having to carry an extra fuel tank.
Move the battery to the console if you are worried about the weight in the stern.
If you don't like waves coming over the transom in the ocean, buy a bigger boat.
Posted by chris55386 on 09/29/09 - 8:28 AM
#3
I have a 4.5 hp kicker on my outrage 18 and it is more than enough for trolling backwards or forwards in any situation. I personally do not understand it when people say that you need anything bigger unless you intend to use it for some other purpose that just trolling. I am also considering adding wave wackers to the transom as i also rarely get a big wave that comes over the transom and beyond. I do plan on moving my battery to the center console over the winter to offset the added weight on the transom.
Posted by Fishmore on 09/29/09 - 7:55 PM
#5
Thanks for your input gentleman.
Tom, I do have both batteries in my console and a 20 gal. gas tank under the RPS and I do miss my 22 whenever I go in the ocean or even Sf Bay, I just could not afford running three boats as I did before so I sold two and kept the Montauk which seems to be the best all around boat for me. However maybe someday I will get a bigger boat again.
Joe, thanks I dd check out the reccomended kickers and the install (nice install by the way). As you mentioned in the article there are people that feel a single cylinder engine has too much vibration but in my testing I did not find that to be true with either the 5hp Honda motor or the 6hp Mercury motor. Both are single cylinder motors and they did not vibrate excessively, In my opinion the single cylinder 4 strokes are definitly a viable option for a Montauk hull.
Chris thanks for that tip on the wave whackers they may be just the ticket, I googled them and it got me thinking that if I added a clear acrylic panel to my inner splashwell that would solve my water over the transom worry and still allow me to run the 7.5hp motor. I might have to try that out instead of changing motors. I figure I can get a sheet from tap plastics and heat it to match the curve of the splashwell along the interior of the transom. Then the inner splashwell would be as tall as the rest of the transom and I would get less (if not zero) water in to the cockpit.
Posted by chris55386 on 09/29/09 - 8:22 PM
#6
I think I read on their web site that they would customize them to what ever boat and trolling motor set up you had, if you wanted to go that way. I had Wave Wackers on my Alumacraft and they had a slot where my transom mount trolling motor fit in they had rubber flips that sort of sealed around the motor. They are awesome especially when you back troll and we in Minnesota do that allot for Walleyes. There is another company that makes something similar also but I cannot remember what they are called.
Good luck
Chris
Posted by Mr T on 09/29/09 - 10:50 PM
#7
I am very happy with the nissan 6 hp 4 stroke on my nauset. 57 lbs. It runs all day on almost no gas, and is solid solid solid.
Posted by JohnnyCW on 09/30/09 - 5:56 AM
#8
As far as taking water over the ransom, can you accommodate a bilge pump? I run my 17' Outrage in conditions that often has me taking in considerable water over the transom. Fortunately with my model year, the splash well doesn't allow as much water as other years but I found a bilge pump necessary after having the boat a very short time. Having to get up on plane every time I wanted to dump the water wasn't appealing to me.
Posted by donp on 10/06/09 - 10:39 AM
#9
Fishmore, I have a 1988 Montauk with a 2002 Merc 90. My Aux is a Merc 8 hp. The 8 hp pushes the boat at 6 MPH GPS at WOT. Going against the tide and wind the motor does at times struggle. I stronly suggest not going less than an 8 hp.
Best of luck.
Posted by Harvey Boysen on 10/06/09 - 6:37 PM
#10
Fishmore
I have had the same dilema. I have a 170 with bow rails so I have installed a Garelick transom mount. I'm debating between an electric and a gas. I do flats/bay fishing and offshore trolling and I'll probably get both and change depending on what I'm going to do.
The Suzuki 6 seems to be the best for a gas. It has a 180 degree range, internal fuel tank and has an optional charger that can be hard-wired incase I run down the battery and can pull from the boats gas tanks.
Please post what you do and results.
Thanks
Harvey
Posted by Fishmore on 10/06/09 - 6:45 PM
#11
Well my next item to try is to use the 7.5 Honda but I have added about 40 lbs (via downrigger weights) to my forward anchor locker. I have also added a pair of splash/wave guards to the low spot in my transom. I made the guards from 1/4" plexiglass sized 7.5" x 12". Will let you know how it works out soon. I submitted a picture of the guards installed but I do not know if Joe will post the picture or not.
Posted by chris55386 on 10/06/09 - 8:32 PM
#12
I would love to see what your splash guards look like, I was on the wave wacker website today and I am seriously thinking of having them insall a set of custom ones for my boat by next spring. Maybe you could post the pic. on your personal page or email it to me??
Chris
Posted by HarleyFXDL on 10/07/09 - 6:27 AM
#13
I had a Yamaha 9.9 4S as a kicker to match the 90 Yamaha 2S on my Montauk. I never had problems with the transom being too low. I feel the engine was more than I needed (~100 lbs). The boat would do about 6-8 mph WOT. I have tried different motors (4 & 6 hp) with similar results. I got speeds between 5 mph to 8 mph, using different hp motors. I feel the most important part of the kicker arrangement is in the prop. I now have a 9.9 Evinrude 4S kicker for my Outrage. I went this big because of the incredible price I got it for. Normally, I was looking in the 4-6 hp range. As soon as I install it, I will post the findings.
Edited by HarleyFXDL on 10/07/09 - 6:28 AM
Posted by Fishmore on 10/07/09 - 8:53 AM
#14
Okay I found that I could add more pictures to my personal page. So the picture of the splash guard is in there. Sorry I did not think of that sooner. By the way these two guards with the screws cost me about 20 bucks to make. The Life Caulk I used to seal it would have added to the cost but I had that in the garage already. It is the last picture on the page.
Harley that has been my experience as well that anything over 4hp moves the boat ok. Under 4hp is ok for trolling in calmer waters. Also as you said the prop made a big difference. The prop on my 7.5 is much larger than on the other motors and that adds to the improved performance in strong currents. I guess that is what the High Thrust kickers are all about.
As far as transom height as it relates to the water it may have something to do with operator weight to as I weigh about 300lbs. Anytime I had a wave come over the transom it was when I was standing in the rear corner of the boat. Once we had me and my buddy who is equally large back there. So I guess adding 600 plus to the transom can be asking a little much. Lets see Kicker 70lbs plus motor 300lbs plus us at 600 plus the total is over 1000lbs on the transom. Maybe that is the real problem, operator weight not kicker weight.
Edited by Fishmore on 10/07/09 - 9:33 AM