Putting a (much) bigger engine on a Dateline Bikini. Any thoughts?

[kwik_uk]

Hi,

I run a 16' Dateline Bikini with a 1000/1150 (hybrid don't ask lol) Mercury IL6. The IL6 has just cracked the water jacket on cylinder 5 :facepalm:

I have a spare 1000SS that I rebuilt about 5 years ago and never ran which I was considering putting on. However there is someone selling a mid 200hp Merc V6 XRi for a reasonable price and I was considering putting this on.

The transom was strengthened last year with extra woven glass on the inside, and also has 1/4" stainless plate bolted through on the inside and out.

I've measured the V6 and it is 65" long and my IL6 is 62" long. I don't think there is that much difference in weight, but I'd appreciate what you guys think?

What would be the issues I would face if I fitted this engine if any?
Are there any things I should do to the boat before fitting this engine?
How does the fuel consumption of the 200hp V6 2-stroke compare to the IL6 100hp 2-stroke?

 

[blifsey]

Re: Putting a (much) bigger engine on a Dateline Bikini. Any thoughts?

Sharp boat!

 

[Frank Acampora]

Re: Putting a (much) bigger engine on a Dateline Bikini. Any thoughts?

Too much horsepower is never enough!

Issues: What is the boat rated for? Do the UK water police enforce maximum hull horsepower ratings? Are you experienced enough and prepared to pilot that boat at the speeds it will attain with the larger engine? Are you expeienced enough to recognise and correct any bad handling habits the hull may have with the larger engine?

 

[jigngrub]

Re: Putting a (much) bigger engine on a Dateline Bikini. Any thoughts?

If you exceed the max. hp. rating for your boat and have an accident, your insurance company won't know you and laugh if you try to file a claim.

 

[tx1961whaler]

Re: Putting a (much) bigger engine on a Dateline Bikini. Any thoughts?

I think you are misunderstanding what the hull rating is really about. It has very little to do with the actual weight of the motor but rather with the torque that the propeller thrust puts on the transom.
The 200 HP will consume roughly twice as much fuel as the 100 HP.
You may end up with a fast, stable rig with a 200. You may also end up with an unstable dangerous rig. I have no idea of what the laws or regulations are in the UK for this type of thing, so I won't even guess.

 

[Chris1956]

Re: Putting a (much) bigger engine on a Dateline Bikini. Any thoughts?

That 1150 is about 300 US pounds. The V6 is more like 450 US pounds. The torque of the V6 is much greater than the IL6. I was unable to see the pictures, however.

BTW I would think the IL6 is either a 100HP or a 115HP motor, depending on the powerhead, but not a hybrid.

 

[DuckHunterJon]

Re: Putting a (much) bigger engine on a Dateline Bikini. Any thoughts?

I have a 200 optimax on a 20.5' boat. I can't imagine more motor on a boat 4.5' shorter. My concern would be stability. That's a heck of a jump in HP.

While it's just opinion, I think that boat would look better with a period correct motor as well. A big XR6 cowl back there will just look odd - again, JMHO.

 

[haulnazz15]

Re: Putting a (much) bigger engine on a Dateline Bikini. Any thoughts?

I think I'd go find a nice 150 Merc if you're looking to upgrade. That's still a decent jump in power, not much weight increase, and should have 150% or less of your old engine's fuel consumption.

 

[kwik_uk]

Re: Putting a (much) bigger engine on a Dateline Bikini. Any thoughts?

Hi guys,

thanks for all of your comments and advice. I have decided not to buy the motor as it really would just be too much for the boat. I really don't like the sound of all the extra weight, or the fact that I'd be chine walking my way to an early grave! My girlfriend took one look at the motor and said that if I bought it she'd never set foot in the boat again!

I'm going to continue the search for a newer motor, but in the meantime finish building the 1000SS so I can at least get some use out of it before the summer is over. Just got the gearcase back from the powder coaters last night and the guy has worked absolute magic on it. He's bead blasted the outer case, and vapour blasted the inside (apart from the machined areas of course). Etch primed then powder coated with a marine epoxy coat. The coating is very hard! I'm going to take my leg, transom bracket and power tilt brackets to get done. The rest of the cowling will just be sprayed Phantom black.

Thanks again for your help guys

 

[kwik_uk]

Re: Putting a (much) bigger engine on a Dateline Bikini. Any thoughts?

I think I'd go find a nice 150 Merc if you're looking to upgrade. That's still a decent jump in power, not much weight increase, and should have 150% or less of your old engine's fuel consumption.

Which model year do you recommend?

 

[haulnazz15]

Re: Putting a (much) bigger engine on a Dateline Bikini. Any thoughts?

Which model year do you recommend?

I'm not an officiando on the O/B's, but I doubt there is a whole lot of difference in the 2-stroke 150's by model year. I'm not necessarily partial to Merc's, but I do see a lot of them around on everything from bass rigs to pontoons.

 

[kwik_uk]

Re: Putting a (much) bigger engine on a Dateline Bikini. Any thoughts?

Well I took the plunge and bought a 1998 Mariner 135. The thing is in very very good condition and came at a decent price.

Here are a couple of pics (although I'm sure you all know what these look like already ):

Just need to buy a new decal set (ouch ?$? ) and it will be like new.

 

[gjmsd]

Re: Putting a (much) bigger engine on a Dateline Bikini. Any thoughts?

Nice looking boat and good decision on the engine. I've owned several this size that have been powered by 115 to 135 hp motors and think even 150 hp is pushing it. These boats are so light they don't need much (and there is always that pesky liability issue with the big motor).

Now if you had asked when I was much younger, I'd have asked "is 200hp really enough????"

 

[mr 88]

Re: Putting a (much) bigger engine on a Dateline Bikini. Any thoughts?

FYI the HP rating of your original motor is about 15% less than your 1998.So you would be going from about 90/95 to a 135 or a 110/115 to a 155 depending on how you want to compare things, at any rate a considerable jump.You will pick up 5-10+mph if propped correctly.Oversize the transom holes by a little bit,then liberally apply 3m 4200 to your bolts,this will keep your transom watertight.Colbalt drill bit or just about any new bit will do the trick as SS is not really any harder to drill than regular steel

 

[pevaguy]

Re: Putting a (much) bigger engine on a Dateline Bikini. Any thoughts?

Mr88, have you ever drilled SS, it is much harder to drill than mild steel.

 

[mr 88]

Re: Putting a (much) bigger engine on a Dateline Bikini. Any thoughts?

Yes and colbalt works excellent.

 

[Bamaman1]

Re: Putting a (much) bigger engine on a Dateline Bikini. Any thoughts?

Point of information. How much speed were you getting with the old motor? How stable was your boat fully trimmed?

The last really fast bass boat I had, it was stable to 55 mph, then it started chine walking. Adjustable motor mount would have got me a few mph more before it got squirrelly.

 

[Sprky]

Re: Putting a (much) bigger engine on a Dateline Bikini. Any thoughts?

The 135 is a good choice! It has carbs with a 1" venturi and will use very little fuel. You will be able to cruise at close to what the other motor ran wide open. I would consider starting with a 23 pitch tempest and work from there.

Don't be afraid to let the motor spin. I ran a 2 litre class which required us to start with the same base that you have. My motor would turn 10200 at the end of the quarter. Your motor in stock form, with a good set up, on a light boat, will twist 7200.

The 135 is heaver than the 200 because of the way the block is manufactured, but will not be an issue. If you "squeak it" You can unbolt the powerhead and bolt down anything 2.0, 2.4 or 2.5 litres from 1982, to the midsection and go....... It's called a 10 bolt tune-up.

Have fun

 

[kwik_uk]

Re: Putting a (much) bigger engine on a Dateline Bikini. Any thoughts?

Warning: thread revival!

Well this project is starting up again now it's getting a bit warmer.

Plan is to get the boat out of the water at the marina and up to the house so work can begin, and quite a long list of work it is!!

1) get the old engine off
2) remove interior
3) separate top and bottom of hull (looks like a nasty job)
4) remove floor
5) rip out the old stringers (found they were only bits of dust holding hands)
6) replace the stringers
7) new floor area up front to hold the battery and twin removable tanks (shifting the weight up front due to heavier engine)
8) new floor in mid (including new seat anchors, may even be sliding if I can find a donor car)
9) new floor in rear
10) sketching out some ideas for transom and knee bracing. I'll probably bolster the glassed in knee braces with two 2" box section stainless brackets
11) new stainless transom plate inside (1/4") and out (1/16")
12) drill the new brackets (anyone got a lightsaber handy?)
13) fit the new engine and ancillaries.

...oh, and I've got two weeks to turn it all around and have it back in the water

I'll post up a work log as I'm going, I think I'll need to so that I at retain some part of my sanity. It's going to be my first time (on my own) with epoxy as opposed to polyester so that should be fun :facepalm:

I need to finish off the 1000SS that's sitting in my mothers garden at some point too. I'm told it's spoiling her view of the trees. Personally I quite like it...

 

[oops!]

Re: Putting a (much) bigger engine on a Dateline Bikini. Any thoughts?

hi buddy......do you want me to move this thread to the restoration section?
or are you going to start a new thread there?

we can walk you right thru the job.

but is you are going to use epoxy....throw out the time line. the epoxy takes 24 hours for cure.....that means every step you do....you will have to wait a full 24 hours for cure before you can touch the area.

2 weeks is not a lot of time for a full gut restoration.....even with such a small rig. being a pro, at 12 hours a day, i would be hard pressed to do it (my self,,,no other workers) in two weeks. but it is doable.

you do realize that going with epoxy will gain you nothing except extra expense right?
the difference between weight over poly and epoxy will be about 3 lbs for your project, ans because the boat is so small and has many curves and corners in a small space, you will never need the extra stregnth that the epoxy will give.