1988 Wellcraft Nova 3 performance notes/questions:
 

1988 Wellcraft Nova 3 performance notes/questions:

When I first bought this twin engine, stepped hull sport boat, it had bottom paint, stock engines (Merc 350 mags), both props rotating clockwise (21P-Alpha 1), conventional thru-prop exhaust and did 55mph on GPS. I’ve always believed this boat was capable of more performance and have taken significant steps in search of greater speed, but have not yet gained the desired gains in performance.

What I have done: replaced both engines with remanufactured Merc 350 mags, installed new IMCO Powerflow exhaust manifolds, stainless risers and thru hull exhaust, new counter rotating lower unit so props now counter rotate OUTWARD, bottom paint stripped off with chemical peel method leaving a barrier coat (primer) that is no smoother than the bottom paint. And now the boat runs great and sounds great but I’ve only gotten 50-52mph on GPS and the engines only rev around 4200rpm (normal operating range should be 4600-4900).

My speculations: stepped hull Fountains rotate their props inward for max performance because it lifts the rear of the boat and ostensibly reduces drag, resulting in higher top speed. Perhaps when both props were going the same direction, some additional lift was present allowing for slightly less drag. The bottom paint I had stripped off revealed a barrier coat probably didn’t reduce the drag. According to a local propeller shop, the props have perhaps too much “cupping” on the following edge. The performance exhaust I installed has probably given the engines additional power potential but have not delivered the desired performance due to factors such as the rotation of the props outward, the non finished hull and the props having perhaps too much “cupping” on the following edge of the props.

Action items: I’m having the props re worked to take out some of the cupping to hopefully gain an additional 200 RPM or so. I’m going to sand the barrier coated hull down to gain considerable hull smoothness. I’m going to switch the prop rotation so they rotate inward to lift the back of the boat.

Anyone care to comment on whether these actions are likely to give me the 60mph or so I hope to achieve? If all else fails I may install different engine cams to boost the horsepower of the engines.

just a couple of thoughts; its entirely possible that the reman motors are not yet broken in and/or making less hp than the old mills. probably not the case but make sure the drive ratio is the same as the old units. did you make your previous speed runs under the same climatic conditions ( elevation, humidity, temp. etc) ? why not try different props before you have the cup reduced? good luck. - jeff

I do not think that this is a stepped hull but rather a straight deep vee. You will need lots of HP to get speed and the correct set up. You need to prop for more RPM. Maybe less pitch but watch your slip %.

Thanks for the input. Props are already modified, so we'll se what happens there. As for the difference in the conditions when I ran 55mph vs. other times at 50mph, I'm not sure exactly. The hull does in fact have a step in it and I'm happy to send out a photo if you're interested. I know this is not the case with most Novas.

Nova III
 

Stott,

I had an 87 27 Nova III in the early 90's we had blast with!! Decent on fuel, ran low to mid 60's on the speedo w/55 gals. fuel(1/2 tank) and it too had a step. We were running 13 3/4" - 21's about 5k rpm's. We were spinning two right hand Alpha's. Not a rocketship but I spent a lot of time on the water when the buddies were working on their faster boats. I sold the boat for $500 more than I paid for it three years earlier. Wish I had that luck with all my toys!

Have Fun!!

Katz

I know a guy with a nova 3... it does indeed have an early stepped hull. nice boat.

he's getting a bit more speed than you, he didn't do motors but did do exhaust and props, tuned everything up, etc. He's only running 55-60, though, not much faster than you're going.

Once the motors loosen up a bit you will gain some speed. A fresh motor will often be a little down on power.

What props are you running? I have a brand new set of Mirage 19's that have never been used if you could use them.

Bobkatz,

Thanks for the input. May I ask if there was any particular reason for you running 2 right hand rotation props versus counter rotation? Also, what was the best mileage you got at cruise speed?

BajaFresh, I'm running 21P - 14" Turboprops. Just had them modified so I'm going to see how these do before making any further modifications.

Stott,

I bought the boat with two right hand drives & props and the boat was extremely reliable & fun the way it was. I never felt the time & dollars necessary to gain a couple mph's was worth it to me when what I had worked so well. I had friends w/blown Cigs, Fountains & Skaters and figured I would never run w/those guys so I went the reliability route. Personal choice nothing more. With that said, had I needed to replace a drive I would have liked to go counter rotating.

I love twin small block boats in the 26 - 30 ft range.

I have no idea of the fuel mileage. I can say it was much better than my friends above referenced boats. They were always B*tchin about fuel!

Add some pics, would love to see the boat, great memories!!

Do I recall that hulll having a hook in it?

Katz

Just for some comparison numbers:

I have a 1987 Baja Force 265;

Twin 350 mags w/ alphas (both standard rotation, which I believe was quite common in this age of boat);

speed on the "wishometer" is in the low to mid 60's, and running along other boats, this seems to be consistient;

I'm turning 5200 rpm w/ 20 dergree props (will upgrade soon to labbed 23's, as these engines are stamped with 4200 - 4600 max w.o.t.

Your boat may be a little heavier(?).

I'm about 5200 lbs. dry.

BobKatz- You might be interested in seeing a photoshopped pic of the new low profile tinted windscreen I want to install. . If you'd like I'll email some photos to you as I can't figure out how to attach them here...and as far as I know there's no hook in the hull.

KenThe Green Keeper- I'd like to think with some tweaks that maybe this could be a 60 mph boat...especially if I can get the extra rpm closer to 5000. I'm getting varying opinions about whether rotating the props inward versus outward will have any effect. My boat is 5500lb dry.

Stott71

you may want to try some different props like Merc Mirages.....they offer alot of bowlift and get the boat out of the water......made a huge difference in my twin sbc 29 Fever from the stock quicksilver props........and I dont counter rotate......you may also want to try some Revolution 4s or Bravo 1s.......

Ive been on this site for a long time and thread after thread prop expert after prop expert reccomend Mercury props for sterndrive boats........with the possible exception of Hydromotives on Fountains.......

Update time! Water test last weekend and stopped to watch the start of RPBA's Jammin on the James poker run.

I got the 21P props back with reduced cup and got some needed rpm and got 55mph on gps. However, only the starboard engine turned 4700 rpm, up from 4500. The port side engine still only turned 4200 like before. The drives are in good condition, the engines only have 60 hrs and the butterfly valves on the carbs are full open at full throttle.

So I'm wondering why one engine would only rev 4200, even trimmed way out. I wonder if one engine is not getting enough fuel or if one carb is malfunctioning. I suppose I could swap carbs and see if the engines run any differently...or check for a clogged fuel filter or fuel line. What else could it be? Thoughts?

Also, I mocked up the chopped windscreen and the boat looks 10 years newer! Lovin it! Templates are at Norva Plastics in Norfolk, VA being fabricated as we speak!

Norva Plastics - Howard Everton - 3911 Killam Ave. Norfolk 757-622-9281

Before you switch the carbs, double check the timing. Make sure they are both on the money.


Darrell.

Hi, I am intrested in obtaining a windshield that you had made...I have the same boat as the yours. If you could please e-mail me with any information, that would be greatly appreciated.
[email protected]

Well it's 5600 pounds empty to begin with. With fuel etc probably pushing 6,000+ pounds.

A 28' 8'3" boat with no platform. I believe it has one step.The big factor is it's actually has a deadrise of 25 degrees.

A true wave hammer but it is a bit bow heavy and the challenge is keeping the bow/transom up. So they put a step on it hoping to provide a running surface that is flatter in the back.

The step is about 22-23 degrees...not a huge flattening..if you get my drift.It didn't work exactly as planned (speed wise). Wellcraft discontinued the model and went to a 23 degree deadrise instead of a step in or aorund 1992 in their 26'er. WIth T-350's it ran 65mph with a 23 pitch Mirage prop.

Your boat needs a prop with lots of cupping to get the transom up. The Hydromotive "Turbo" prop at 21 pitch. was the best for the boat with T-350's and it would get to upper 50's. A 23 pitch prop would overload the alpha drives.

The boat actually needs to have the power to turn a 23-24 pitch prop to get it excited at the top end.My suggestion is to enjoy it for what it is...or Whipple it up to a total of 800+HP and then you will see numbers around 70+mph with bravo drives.

I had one and drove several...fyi...advertised top end was not what the gps read...

Alright, I have the same boat but different power. I have twin 300 tempests, and regular replacement se 106 drives with 21 p cupped props. I am running 63 mph on gps @ 5200 rpms. I think I want to drop it down to the 4800 range. I tried running some 23p clevers which dropped the speed to 60mph. I like how it comes out of the hole with the 21p props, however I dont like the 5200 rpms @ wot. I like the 23p props for the wot but I am not impressed with any of the performance. Is the another prop I should be looking at?

The boat is very sensitive to cupping and pitch as you know. Cleavers don't work that great. A four blade would be better with a big block I feel..

I think you need what is shown below: High rake and progression pitch. It will give you the best dead start/ acceleration..bow lift .all the way to top end. It will put your step to work...and you will get the speed you want at lower RPM's.

http://www.miwheel.com/MIWheel/produ..._main.htm#rapt


Get a 21p and you will be all set. Outside rotate them.

Thanks is there anyway to try them before I buy them. I dont want to shell out almost a grand and find out they are not what I was looking for. I also talked to the prop shop around here and he said he could re-pitch my props to a 22p for $150 a piece. Any ideas on that.

I run 23p vented laser 2 on tha 29 scarab twin sbc. New drives last year 1.47 : 1 I believe is the new ratio , was 1.5 , 350 carb mags. Boat runs a solid 60 @ 4400. Don't think I'd go up in pitch if you can't turn up the 21's

thats the problem, I am turning too many rpm's now

Laser II's do not have enough blade surface area in my opinion. I ran in a baot like yours...you need a 21P with lots of cupping and lots of blade surface area.

A great prop is the hydromotive Turbo if you can find them...i found a dealer who let me try a pair out first.


Check this out....then give them a call...

http://www.land-and-sea.com/marine/s...ck_results.htm

I called them but they are not in the boating business anymore. They dont do props or those stern jacks anymore. Any ideas? I was able to talk to the tech for a bit, and he said if I could get some of those stern jacks my boat would drastically increase in performance.

Hello All,

It's been about 2 years since my original post, been busy getting used to the demands of 2 kids (now 2 and 4) and a new job (Square D Clipsal residential lighting/home automation). Anyway, I rebuilt both carbs (in retrospect this seems to have been unnecessary) and still need to sand the barrier coat smooth on the bottom of the boat for hopefully a few more mph. The most notable change is the new vinyl graphics (see same Thread on speedwake.com for photo or e mail me at [email protected] and I'll send you a copy. Cool I think!

Hello all... I JUST got a nova today...It's a spyder, 1988 which is several hundred lbs lighter than the nova III. Its got the twin 350's and the boat is TOO DAMN FAST.... Idk what to do....even my dog just wants off! At around 3000 rpm, we're doing about 44 mph....when you hammer it, LOOK OUT! I cannot top end the boat yet because it gets "loose" in the chop of Lk St Clair. I can't ride out the r.p.m. band and see what she will really do because she doesn't feel safe. I ran with a 34 ft formula this afternoon, and made that boat look slow.... This boat MUST be modified?? I have NO CLUE what could be done as I have only had the boat one day and it's scared the hell out of me and my dog... The surveyor said..." you buy this boat or I will" I bought it... Will some HUGE trim tabs like I see on the bajas and fountains help?? It's 25'9", 5200 lbs dry... Any ideas>???

I know this post is dead its been years but I have a 87 Nova III with twin SBC's and I am building some wicked 450hp SBC's for it. I am interested to see what you guys think it will do and also STOTT I seen your windscreen and really like it. I contacted Howard and he needs the name it was in to pull it up.

MuddyToy I also contacted the manufaturer as well and he doesn't even remember making it. I am still currently looking for someone to make one. I have an 86 model with T350's and best I have seen out of mine is 56mph on GPS. I would like to get rid of the bottom paint but in further checking someone did a crap job of sanding. The hull is ruff on the bottom so I want to re sand and go with performance epoxy.

I have a hull for sale for 1000 with decent interior no power or trailer for 1k if anybody interested. the motors were (are) about 350 hp each. flat eutectic pistons, dart 007 heads, performer (non-rpm) intakes. ls-4 (I was told) cams and glm alum exhausts. did 63 at 5200 gps. 23 mirage props.