$100 Invader

[inthedirtagain]

So I picked up a 1984 Invader 181BR with the OMC 3.0L and model 400 outdrive. After a few minor repairs, I was able to splash for the first time around the 4th, but was not impressed with its performance. I'm not sure how accurate my tach is, but it wouldn't go above 4k with a 3-blade 15p. This gave me a top speed of about 29-30mph. I was expecting closer to 40. The boat seams a little heavy and sluggish, so I'm not ruling out the possibility of extra water weight.

I've double-checked that throttle is opening all the way, my compression is good (135-140 lbs), timing and mechanical advance is spot-on, as are the points/dwell. Varying the trim didn't make too much difference, either. All of this was with a family of 5 (about 700 lbs) and a full tank. I had expected this prop to spin the motor higher than 4k. We pull tubes and knee/wakeboards, so WOT almost never happens. But still, I expected more. It planes out pretty quick, so I'm not sure that moving to a 4-blade or even stainless would help. Your suggestions?

 

[Scott Danforth]

I would actually weight the boat. you could have water soaked foam and rotten stringers below the deck and be carrying around an extra 1000# of water.

Per http://boatspecs.iboats.com/Invader_Marine__V181__1984/bp/66b45427 your boat should weigh 2100# dry. if you have a single axle steel trailer (aprox 1000#), you will be about #3100 dry.

that motor and drive combination on my 17' Avanti would hit 42mph at a bit over 4600 RPM swinging a 19P 3-blade SOLAS stainless prop with 4 people on board. My Avanti was about 6" shorter and 300# lighter, however you should be able to get higher than 30 with your combination. And with a 15P pop out on the hole shot. you may have to hit the hole shot with the drive all the way down and raise the drive as the boat starts to climb the bow wave with the 3.0. That was my normal operation pulling skiiers

 

[steelespike]

I have to agree with Scott. Does the boat get up on the water when you trim up? Or does it lay down flat like it is glued to the water?
Lots of spray like it is plowing through the water?

 

[inthedirtagain]

Laying the drive down and then trimming up is usually what we do when I'm driving. When my wife is pulling me on the kneeboard, I just leaving the drive at about 25%. This gives her the holeshot without having to fuss with it, and gives me a better wake to play with. If I get a chance, I'll try and take it to the recyclers to weigh it and the roller trailer. It does seem heavier behind my truck than it should.

 

[Scott Danforth]

I had to put the spotter in the bow of my boat when someone else drove because I told them to leave the trim alone. you may also want to try that after you weight the boat

 

[inthedirtagain]

Well, not going to get the chance to weigh it or do much with it at all now. Came into a financial mess and put it up for sale. Had about 30 emails in 24hrs and consequently sold it for $1500. Not a bad return on my $100 investment.