BWM 18 & 150 optimax?

[Daniel]

Thoughts gentlemen please (and ladies).

I have been thinking about getting a bigger RIB (and more eficient engine) for a while, but since the 18 foot'er fits nicely on the drive i have taken to looking at Optimax / HPDI to upgrade the current outfit...

...I have stumbled accross a 150 Optimax and quite fancy putting it on the back of my boat. Yes i know it's big, but is it too big???

I am quite sure (been told by a few people and http://www.divernet.com/boats/survy299/tabboat.htm) that this little boat was rated up to 150.

The facts:

Yamaha 130 (wot i got) 167Kg
Mercury 125 158Kg

Yamaha 150 v6 194Kg
Yamaha 150 v-max 199Kg
Yamaha 150 HPDI 216Kg

Optimax 150 201Kg

By my reckoning this is not very much more than a 'standard' 150 which is what the boat is rated at so all should be OK??

Anyone seen / owned a BWM 18 with an engine of this size?

All comments and suggestions of insanity invoted (but beleive me this baby will FLY!)

Daniel

[Pete7]

Yes, oversea, another BMW rib (and currently for sale on Ribnet) orginally had twin 40 mariners fitted. Strangely enough it didn't go very fast with eight divers on board so they fitted a Johnson 150 V6, one of those imports from the middle east which all seem to have gone bang in a big way. Anyway it now sports a 135 merc.

However the BWM were budget boats built to a price. Are you sure you really want to hand that weight on the back of the boat and will it effect the handling ? I am about to put a 150 opti on the back of a 6.45 ribtec but it has two huge stainless steel ribs to re inforce the transom. Is there a lighter 4 stroke perhaps like the Suzuki ? or even something from Tohatsu, or even the Yahama 100 / 115 4 stroke.

[Alan]

I had a 150 Opti on a Deep Sea 21 which was fine. Just about the right power to weight ratio. We originally had a gulf import Johnson VRO until that went clunk and expired in the middle of the Solent! We had already reinforced the transom with a dirty great stainless plate bolted through the knees before we fitted the opti.

But on a DS18? Hmmm, I reckon thats a bit much. Only other chap with a DS18 I knew had a Johnson 115 so you already have more power than he did!

Opti's are good engines, way more economical than conventional 2 strokes. And way way more economical than the VRO. I used to reckon on about a litre a mile. Interesting thing is that having now gone up a boat and engine size to a 200 Yam HPDI I still get a litre a mile. So bigger boats 'aint neccessarily more expensive to run! Of the two engines the Yam is the quieter and better engineered IMHO but they are considerably more expensive.

What are your reasons for a bigger boat? If they are the usual around more comfortable/seaworthy for longer trips etc then spend your money on the bigger boat, making sure you get an opti/ficht/hpdi for economy.

My 2ps worth anyway!

Alan