Engine for 4.2M Polaris RIB

mantamike · 28 March 2008, 17:04

My first post. I just ordered a 4.2M Aluminum RIB from Polaris and am struggling with my engine choice.

Here is my challenge. I am using this boat with an electric boat loader with a custom rack over the canopy on my truck. The boat will be tiller operated with one bin seat. The boat is a aluminum hulled and 2.3m (6'9) wide by 4.2m (13'6) long. It weighs 127kg (280lbs). The boat has launching wheels which will help with mounting the motor.

Because it is being carried on the rack, I have to physically load the OB. I have a custom dolly for the motor to make things easier.

Obviously weight is a huge issue, and after researching I have narrowed my choices to the following:

Option 1: 2 Stroke Mercury 30HP ELH- Weight: 114lbs. $2,645 New
Option 2: 4 Stroke Honda 30HP- Weight 159lbs. This is the lightest 30 made, all others are way too heavy. At 159lbs, it is questionable on portability. $5,000 New
Option 3: 4 Stroke Yamaha 25HP- Weight: 145lbs. Is this enough power? $4,400 New

I would love a 4 stroke for all the known reasons, but price and weight are huge considerations. Will I be disappointed with a 25HP?

As for use, the boat will carry primarily two adults, two small kids (5), and a dog. It will be used on rivers, ocean and lakes. I would ultimately like to carry 4 adults and the two kids.

Thanks in advance for any help.

Zodiac Joe · 28 March 2008, 17:18

buy a small jet ski trailer they are about 800 dollars how much is your back worth to you and you can launch by your self with ease.

mantamike · 28 March 2008, 17:22

Obviously if that was possible I would have done that. I am towing a 30' travel trailer.

John Kennett · 28 March 2008, 20:27

The biggest motor that I would want to lug about with any frequency would be a 25hp 2-stroke. There are still a few around if you're quick.

Your boat isn't going to be lightning fast with a 25, but I reckon that it would be perfectly usable and you're going to have a compromise somewhere.

John

PS We want pictures of your rig!

prairie tuber · 29 March 2008, 04:41

First off, great decision on Polaris - they make excellent quality products. I believe a 13'6 aluminum hulled Spirit is rated for a 40 hp maximum, I imagine a 30 hp should move it OK if it isn't heavily loaded. If you can find a used 40hp 2 stroke from Nissan/Tohatsu (~155 lbs) or Yamaha (~170 lbs) the weight is pretty reasonable. A tillered Honda 40 hp is ~ 205 lbs and may also be worth considering given it's fuel efficiency.

If you will be loading and unloading the outboard with each use, you may want to get a spitzlift which will save your back. Even while using the launching wheels, you will find yourself bearing a pretty substantial protion of the boats' weight while holding up the bow off the ground.

http://www.spitzlift.net/products/universal.htm

bedajim · 29 March 2008, 08:31

Quote:

Originally Posted by mantamike

. I am using this boat with an electric boat loader with a custom rack over the canopy on my truck.Thanks in advance for any help.

Sorry bit off post but do you have a picture of the rack and electric loader?

James

Poly · 29 March 2008, 21:13

Mike,

I have a 3.9m rotomolded plastic boat (v hull, sponsons etc - so similar to a true rib), IIRC it weighs 120kg so should give a reasonable comparison to your boat. It is powered by a 2stroke 20 HP yam, and gives 20 knots at full throttle with 2 adults and 1 child on board (and a reasonable amount of kit, fuel etc).

So yes, a 25 HP should be OK unless you are desparate for speed.

But my engine is seriously heavy for one person to lift. I think it is just under 50 kg. Other than your option 1 - then unless you are incredibly strong/fit you will not be able to lift it properly, never mind actually position it on the transom in the water. Perhaps there is a way using some sort of hoist?

Poly · 29 March 2008, 21:45

Mike,

Just had another thought - with 120kg of boat + 50 kg of engine and maybe 50 kg of other kit etc, I can JUST (and I really mean just, for about 10seconds) lift the front or back of the boat to adjust its position on the trailer. Lifting the front of the trailer is easy enough so transom wheels will help you BUT I think it will be hard. I don't think I could pull my boat up any slipway (no matter how shallow) on my own - the trailer is obviously more weight again but that is with some decent wheels and a jockey wheel on the ground.

This might sound crazy - but is there any way you can lower the boat directly from your "truck" into the water?