Need advice on new motors

[coolbox]

Hi guys
I am new to the forum,but need advice.
My father owns an Ace craft 18.6 seaglider. Currently running 2 mercury 60 HP bigfoots. It is well balanced with enough power. He wants to upgrade to 4 stroke motors to reduce fuel consumption. We are looking at Honda bf 60 at R 87 000 or mercury 60 HP at R 77 000.

My question is should I go for Honda or mercury or should I go for Suzuki df 70 or yamaha f70

I prefer the Suzuki but was wondering whether the extra weight will make the boat heavy at the back or increase fuel consumption.

I am launching at a harbour, but is the 60 HP enough for the boat.According to me the boat has foam and not bottles but is still heavy. I do not have the weight

Any feedback would be appreciated

 

[thika]

Hallo Coolbox
Welcome to Sealine
Your dad has good choice in boats...post a pic of her on the Ace Craft page and a bit of her history please

My question to you would be how many trips would you need to do to save the additional expense on the fourstrokes? Assuming the current motors are in reasonable nick of course. Or is fuel capacity maybe an issue as well?

The answer to your question is to buy the right weight motors with the largest displacement as this determines the torque. Smallblock motors have to rev higher to make horsepower, which is not needed at sea. Then they have to do all kind of tricks with gearboxes and propellors to make up for the lack of grunt needed to keep a boat at steady speed in normal ocean conditions.

I did some research on motor torque vs. weight for some of the makes about two years ago. I will find it and post on SL.

I would go for the new Mercury 80HP. It is the same motor as the 100Hp.
It is simple and very strong. Also 5 years guarentee.

 

[IWyk]

Will take a long time to recuperate the cost involved just by reducing fuel consumption. Same size four strokes will be heavier with much less crunt/power at the bottom. Personally I would rather stick with the two strokes unless they are shot and you need to replace them. You will never recover the money on fuel saving unless you use the boat a LOT.

On some boats, there may not be a sufficient fuel saving. Just my personal opinion. I like my two strokes.

 

[coolbox]

Hi Thika

Seems like my reply did not go through.
We owned an 18 ft acecraft one of the first fibreglass hulls I think it was number 52 or 56.
It was fitted with a single mercruiser 160hp 4.1l straight 6, we later replaced it with a 140hp 4 sillinder chev.

We then bought an 18 ft cat with 2 60hp mercuries but kept the acecraft. After my dad retired he wanted a boat with low fuel consumption and tried to get the acecraft working again.
Because of recurring problems he bought 18.6ft seaglider hull only and fitted 2 60hp mercury bigfoots. This is an excellent combination. He doesn't need to upgrade the motors,I think he is just itching.

Currently fuel consumption is 1l per km on average. My question is whether he can get it down to .6/7l per km by fitting 4 strokes.My advice was to fit Honda bf 60 4 strokes my concern is that the power will not be there. Other option is Suzuki df 70 that will mean 96kg on the transom.

Regarding the mercury 80 HP it weights 181kg I visited a guy in Brits who has these motors fitted his complaint was water coming in over the transom maybe the add will be recognized by someone the boats name was Triple D

 

[thika]

Thanks for that bit of history

Do you guys have pics of those old boats?

The Suzuki DF70A weighs 158kg and is 1502cc

The New Merc 80 weighs 163kg and is 2064cc

It makes peak power at around 5000 RPM only...one cam, 8 valves.

You cannot even begin to compare the two...it's like Fiat against Iveco

To give you an idea, the Suzuki DF140A is only 2044cc

Now you tell me which engines are working themselves to death

Your current outfit is running at 1,85L/NM which, with the lower price of petrol is neither here nor there

Sure you will get it down to 1.2L/NM with 4strokes, but what's the point?

If you were doing 100NM trips or were commercials, sure, but are you?

 

[coolbox]

Morning Thika

Thank you for the advice,for now I am sticking with the bigfoot mercury. I will contact mercury and find out about the new 80hp

I will also post some photos
Regards
Coolbox

 

[benniejordaan]

My opinion...

Honestly they are all good. Honda, Suzuki, Mercury or Yamaha. buy what you are comfortable with or check for the best price. You don't get bad 4-strokes. Some are a little heavier and cheaper but I don't believe there is a huge difference anymore.

 

[QuQ]

Would motors exceeding 150kg a piece not be too heavy for that boat? I would do an exercise and place bags of sand at the stern to the weight of the additional weight that will be added by the newer 4 strokes and see where the scuppers are in the water and how the balance of the boat is affected. If it can hold the weight, my preference would be the Suzuki 70 (155kg) with a 1.5L block. If they are to heavy, and I suspect that they may be, then your next best would be the Yamaha 70 at 117kg, or even Merc Bigfoot 60hp at a similar weight.

 

[pork pie]

Suzukis rock!