Hi my name is Scott, and I have a speed problem. :-)
 

Hi my name is Scott, and I have a speed problem. :-)

I have a solid 500+ hp engine pushing a 19ft boat (1972 step boat) with a VP 280 outdrive and even running on the last few inches of the hull I can only get the thing to 53 mph on gps (properly trimmed). The WOT process is one where it is power up until I hit ~ 52-5400 rpm and go no further since the engine i still pulling hard…my thought is I need a “taller gear”, or in this case more pitch in the prop. The 280 is set up for a left rotation prop and I have yet to find one with a pitch beyond 23 that fits the vp spline pattern, so that is what I run with.

My goals; 1) more speed, very nice to have is 2) good enough handling (better than I have now) to get in and out of tight docks without always wanting to go to the right.

My thought is that I am simply under propped and need to get something in the 27-28 range.
SOLUTION - if this is likely - find the elusive prop

i also wonder if I am limited by the VP280, meaning, if I start to work the engine vs spinning it I’ll bust pins etc because the 280 probably was not built for 500+ hp?
SOLUTION - Replace the outdrive?

if the outdrive needs to be replaced, can an upper and lower be tacked my existing VP housing? would this make sense? If this made sense can I go with dual rotation where at the cost of some top end I get better control of the boat especially at slower speeds?
SOLUTION - if all true. get VP parts ????????

If changing the outdrive is the needed solution, should I swap it over to a mercruiser solution? Bravo 1, 3 xr,?

Am I on to something, am I sliding further down a rat hole (wrong direction)?

Thanks!

- scott -

Welcome Scott. The coffee and donuts are by the door. haha!

Outdrive is a major hindrance, in my humble opinion. Never designed for the speed or hp, and certainly doesn't offer the prop options (pitch or style) necessary to get much past where you are now. The Merc gurus can talk about the xrs, etc, but 500hp exceeds the Alphas, so most economical would be to switch to the Bravo I I believe. You still have to consider it is a 1972 boat, so an option may be to buy a newer boat with the drive you want and put your power in it?

CDShack - that is another option I am pursuing :-)

Got questions. What’s a 1972 Step Boat? I ask because I have a 1972 Allmand SuperNova. About the biggest, heaviest, wideset 19’ boat on the market back then. BBC, Volvo 270, 63mph.
You say “properly trimmed”, You do have real hydraulic trim? The Volvo 280T?
“Left hand rotation” is your steering on the port or starboard side?
“23P prop” what kind of prop are you running?
What are you getting the 500hp out of?
This is the deal. A Volvo has its limitations but for the most part they can be overcome. The real issue for you is if you want to change drives to something newer. Over all it would be better but is it cost effective? A new drive will require everything from your motor’s flywheel back including your bellhousing to be replaced. Transom shield, transom, transom fiberglass (exterior) paint/gel, trim system (pump and lines) and outdrive. That’s a lot of change and dollars so if you are going to do it stop where you are at and do it. No reason to throw good money after bad.

I think you reached your limits with that boat. Best to sell and move to more efficient hull and updated running gear. No reason to put more money into a boat that is 40+ years old

if you're dead set on keeping it, put a blackhawk on it with a 1.36 gear and 29 or 31 p props, with the duo prop it will eliminate nearly all the issues you speak of.

Find a perf boat with no or bad engine. Or underpowered with small block. Then sell the 19 with no or other boats engine.

Is that speed with just you in the boat or you and a bunch of skanks and booze?
What make is the hull?

f_inscreenname - long time, not talk! This is too funny, this is your old boat! :-) Let me see if I can answer your questions.

1) by “step boat” I was implying that it loves to get air/lift under it and ride on the much flatter very rear of the hull (btw - to turns out it is a 1969 monza, not a 73),
2) The block on the original 454 cracked so I had a nascar/marine race engine builder craft a solid 550hp from a new 454 block. When dropping this engine in, I added about another 200hp into the dynamics and the suitability of the 280 started to become clear (it is a 280T)
3) port side steering
4) the 23P prop is the SS volvo. I also have a 21p solar you recommend.

As for speeds, when running with the initial motor I could get it to ~ 45 mph/gps. When I put the 550hp in it, all I could do was 53mph/gps….I also had my mechanics test drive it and they got the same readings…they could not understand why it was so slow either

I am not looking to change drives to get something “newer” per se, I am looking to: 1) capture the speed I should have, 2) have better control/maneuver at slow speeds, especially @ higher pitches, 3) get something a bit more reliable/less failure prone.

Since writing the post I have found a VP 290 DP locally ($1500), it has everything from bell housing to prop. I am in the process of cleaning this up/repainting it and will be handing this overt my mechanic to get installed. The 280 is a boat anchor compared to the 290, that alone should give me a few mph :-)

My goal is a solid 65mph/gps and much better maneuverability around docks (and I should also get a fuel economy boost)

My plan remains to run this little Monza as the Bad Ass MF it is :-)

Thanks!

- scott -

I am in the process of shopping for another boat, but it is not with the intent of replacing the monza, I plan to keep this as a 2nd boat for as long as I can.

So, I have now solidified my plans to put the VP 290 DP into the Monza. Is there anything noteworthy that I should be considering with respect to installing and running the VP 290 DP? I do want to get rid of the crappy black props and get a proper stainless. I am fairly certain the engine can spin a single prop up to ~ 27p (guessing based on what was left when running a 23P) but I don't know how this translates into a duoprop?...SO, if you made the move from a single to a dual prop and your single ran fine @ 27P, what would you put on the DP?



iliveonanisland - is there a boat without skanks and booze? The hull is a monza & I tend to believe it is a hull used by other go fast boats of this era.

@ TOMMYMONZA - if you happen to see this, do you know anything about the hull of the 19ft Monza? I believe you mentioned in another thread I have going that he 26ft'r uses the same hull as the century ultra II?

dereknkathy - This is an option I have been considering. I have found a few classifieds for hulls that I would be interested in, but so far no responses. Even if I did go this route, I would look to put another (non performance) engine in the monza, it is a great little boat and I had it all reupholstered last season..it would be perfect for kids or someone looking to putter around in a cool looking boat.