Repower 21
 

Here is what I got want some opinions.
21' seacraft 2000 (i think or 2001). Right now 200 optimax on the back that we are going to re power.
I really really do NOT want to go with another merc. That said I think i am down to the following
200 etech
175 zuke
Want to go 4 stroke but afraid the 175 zuke may be underpowered?
Any 4 stroke yammy is going to be to heavy same with honda. 150 fourstroke is to underpowered.
Max weight on transom is 550 (i believe?)
Was curious if anyone had any experiences or opinions on this boat/or engine.
I am not trying to start an engine bashing thread.

also
there was a pdf file of the 21' seacraft spec sheet floating around this site can't seem to find it.

Never owned one, but i think a Zuke is a fine engine. I think the 175 weighs around 475 lbs and it's still a 4 cylinder.

I think both the 175 etec and 200 etec are 6 cylinders and both weigh in around 435 lbs.

If you are running a 200 opti now, and you like the performance i think you will disappointed with the 175 Zuke. 4 strokes in general just don't have the balls of a 2 stroke.

If you don't want merc, but you like the pep of that 2 stroke opti..........i think i'd be checking prices on a 175 and 200 etec.

Not to be confused with the original SeaCraft 21, below are some details on the recent vintage SC21. It's a different animal than the SC20. 10 " longer, 6" more beam and 900 lbs heavier.

http://www.bustersmarine.com/SeaCraft/seacraft21CC.html

I think you get 45 mph, and close 4mpg at cruise with either option. The etec is a bout 40 lbs lighter than the zuke. The gear ratios and subsequent propping allow the zuke to swing more prop, im not sure if its enough to offset the "pop" mrobertson mentioned.

That late model 21 is basically a shortened 23, so it's got more beam, weight and deadrise than a 20. The small block 2.6L V-6 E-Tec is a great motor with a far better power/wt ratio than the 4 cyl. 4-strokes, and almost too much power for a 20. However you might like the extra torque of the 524 lb big-block 3.3L V-6 better on the 21; although it's 22% more displacement, I suspect actual fuel burn of a lightly loaded motor will be within about 10% of the smaller motor that's working a lot harder. Optimum cruise on the 2.7L is about 3700-3800 rpm which gives me about 25 kts at 36-37% throttle opening on my 20. I can easily get on plane at about 45% throttle. I averaged 4.3 mpg on my 700 mile S. Fla. circumnavigation trip a couple of years ago. We had flat seas, but I was loaded heavy and also cruised at about 30 kts on some long open stretches where fuel economy was not a high priority. Although my Seafari is the heaviest of all the 20' models, the same motor would have to work much harder on a 21.

The 200HO and 225 are strong running motors and very conservatively rated. The "225" is actually about 245 hp and I suspect the HO is probably close to that since they're the same block!

Mr robertson that is one of my concerns.....is that 4 cylinder going to be enough HP for that boat.
Boat is used mainly in mid bay area with a couple close offshore trips out of OCMD. Mainly fly fishing and light tackle. So top end speed is not a priority as much as efficiency is. Also hole shot isn't either as long as it will plane with a heavy heavy load.

Thank you mcgill that is it.

Any other opinions?

I believe the Yamaha 200 hpdi is still available as well. 475lbs

200 hpdi
 

Fished a lot on a Regulator 21 with a 200 hpdi. It was a great motor and would probably do well on a SC21.

Her are a couple of performance tests on the same model boat:
http://www.suzukimarine.com/en/Produ...20Open%20DF175

http://www.evinrude.com/Content/Pdf/...orts/PE684.pdf

I would expect the SeaCraft performance to be a wee bit better than that of the Dusky but the Dusky benefits some from the bracket. The 4 cyl zuke acutally has 250 cc more displacement than the etec

21 repower
 

I just went thru a repower last summer. Have a 2000 21 that came new with 200 Opti. After issues with Opti decided to repower- all your points are correct- 4 strokes are too heavy for this model and I didn't want to go with another Merc- So, went with a 175 E-tec. Now have about 180 hrs on it- great motor, very quiet, good on gas. But- in retrospect I wish I had gone with a 200 Etec. Top end is 31 kts. @ 5400 rpm's which is fast enough for me, but boat just feels a little underpowered. Cruise is 23 kts. @ 4800 rpms. I used to cruise at 23 kts. @ 4000 rpms with Opti. Like I said, boat just feels a little slugish unless you are at fairly high rpms. I tried to save some $ by going with 175 and since the year after I bought my boat SeaCraft starting selling the 21 with 150's on them as standard I expected the 175 to be fine. Always thought the 200 was more than I needed but it was probably the right fit. Like I said, overall very satisfied with engine but would be totally satisfied with a little more power.

Sounds like what you really want is a little more mid-range torque for that relatively heavy 21, and that's why I recommended the big block 3.3L E-Tec, in either the 200 or 225 hp version, instead of the 2.6L motor. When any motor is tuned for max horsepower, the required port geometry (or cam on a 4-stroke) is generally different than it would be if the motor was tuned to maximize mid-range torque. I suspect the 200 hp version of the 2.6L small block motor is tuned for top end HP, so it might actually have a little less mid-range than the 175. Some very knowledgeable techs on the E-Tec owners forum have said that on the V-4 version of the 60 degree power head, the 115 hp motor actually has more mid-range torque than the 130 hp version of the same basic power head.

Gillie, that's a great comparison. I was frankly surprised to see the E-Tec beat the Zuke on MPG, but as you pointed out, the extra displacement of the Zuke probably doesn't help it's fuel consumption. I would suggest that there are a couple of other items that should be considered in that particular comparison:

The quoted weights are dry weights, which means no props or oil in the motor. Since the Zuke crankcase holds 8.5 qts of oil, that's another 15 lbs, so it's true weight for comparison to the E-Tec is 500 lbs! The 524 lb 3.3L motor is therefore a much closer match to the Zuke than 2.6L version in terms of weight! I would think the 21 could easily carry a 500 lb motor with it's 8' beam.

The fuel consumption of the 3.3L 200/225 HP E-Tec is probably closer to the Zuke, but one other difference on the E-Tec's is fairly significant . . . they run an extremely lean stratified charge mixture below about 1500-1800 rpm, so the fuel burn is less than any 4-stroke motor at low speed. BRP says the engine time-at-RPM data stored in the E-Tec computers show that most motors spend about 60% of total run time at low speed, and that's definitely true on my own motor. This means that even if their cruise fuel mileage is less than a comparable 4-stroke motor, the overall total fuel consumption is actually very close because of the significant differences in low speed fuel burn. Denny

Both good points, Denny, I concur the 21 shouldn't have any problem with the weight of either motor'
I think what got me was both BRP and Suzuki claming a top end 10mph higher on that husky Dusky than what Pair of Jacks gets on his 21. Granted the Dusky's bracket benefits it speed, but 10mph on a heavier rig???:confused:

Black jack, how high is your motor mounted and what prop are you running?

It seems Bigshrimpin was getting near 40 on his 23 with his 360lb Merc 175

One other thing I noticed on the E-Tec powered boat: It only turned 5375 rpm; the OPTIMUM rpm for a 175 is 5500-5600, so neither the test Mako or Pair of Jacks is propped right, and that might make a big difference on a boat that "feels sluggish"! The Viper is not BRP's best prop for fuel economy and low speed planing, although it might give the best speed. My experience is that over-propping may give a little better MPG, and maybe top speed, but at the expense of low speed planing ability and holeshot. My pick would be a 15x15 Rebel prop for better fuel economy and more stern lift, although my dealer says his experience is that, while it's a great prop for the big block motors, the small blocks don't have enough torque to turn the big blades on the Rebel unless it's on a light boat. Would like to try one on my boat because if I can turn a 4B 15x15 PowerTech, I'd think I could also turn a 3B Rebel of the same size.

A bracket is typically worth about + 3 mph in top speed IF motor height is correct, so that doesn't explain the ~10 MPH speed differential between the Mako and Pair of Jacks. Moesly claimed his VDH was about 10% faster than a conventional deep-V with same weight and power. I think that's based on the Moesly 21; not sure it applies to the Potter /Tracker 23 and 21 because they are different animals, with different heights on the vertical steps and different angles on the panels. At any rate I would at least expect the Mako and Pair of Jack's SeaCraft to both run about the same speeds with same motor IF weights are similar and they're propped correctly with the right motor height. I suspect that the Mako may have had full fuel tanks but nothing else on board, while Pair of Jacks is probably carrying a lot of extra stuff. Motor height is also real important and the extra drag could knock the top end speed down by several mph if it's mounted too low. For best performance the AV plate needs to be DRY when you're up on plane at optimum trim.

I can touch 40mph with one person, trimmed out, and 70 gallons. 1986 Merc 175 Powerhead, on a 2001 200hp mid section, 1.87 ratio lower and a mirage 15P. 5800rpm.

That Dusky is very similar to a wellcraft v20 hull which is smaller hull than the seacraft.

21 Repower
 

Engine is mounted on 2nd hole from top- I've checked anti- ventilation plate on plane and it's right where its supposed to be- engine came with 14 1/2 x 15 pitch no-name prop (my fault for not catching this). I've had a couple of people familiar with E-tecs tell me that a BRP prop will make a difference and I intend to re-prop over the winter with a Rebel 15 3/4 x 15 pitch prop. I'd prefer more mid-range and high end speed -less concerned with hole-shot.

21 Repower
 

By the way- the top end speed I quoted of 31 kts. was with 85 gallons of fuel (out of 95 gal. capacity) and just me on the boat but with all my fishing gear/bags/etc.

AV plate is bone dry (above water) while on plane.

I repowered my 21 with the 200 etec in 2005, had some corrosion issues and BRP sent me a new lower unit, quiet, fast very nice, does not spin over 5,300 but that is the prop, gets up real fast. Would do it again.

Your 85 galllons is a lot more weight than the 30 gallons used in the 2 motor tests on the Dusky 203 so comparing your rig to those is not very accurate, and obviously the hulls make it "apples to oranges." Bigshrimpin mentioned the Dusky is smaller than the SeaCraft. The specs had led me to believe it was a littler bigger, so throw my assumption is out the window.

Sounds like you're dialed in on motor height. 31 knots is nearly 36 mph.
I simply thought a 21 SeaCraft hull would out perform the Dusky on the top end.

I posted the 2 tests for capnkid to compare the 2 motors on similar hulls. The test were done 68 and 95 deg temps so that alone would make some maximum performance difference.

Your real world experience with the 21 and 175 etec motor are the best info capnkid could ask for. Your suggestion of a 200 etec makes good sense.

Regarding props - if you make the change, be careful with that bigger blade. I don't know the two props in question, but if you're currently at 5400 rpm, a bigger diameter might set you back.

21 repower
 

Ah, the dreaded prop- are you saying that going to the larger diameter prop will reduce rpms? The reason I was considering re-propping is that I've been told by a marina service mgr. and some others that the no-name prop is inferior to the BRP REbel and because of the design of the blades on the BRP that prop will "grip" better thus reducing slip and increasing power- they did not seem to believe that by going from 14 1/2 inch diameter to 15 3/4 would reduce rpm since I'm keeping the same 15 pitch. Now if you guys are telling my otherwise, then reducing rpms is something I'm not wanting to do obviously. Opinions??

You obviously have a 3.3L 90 degree big block version of the 200, since the small block 60 degree motor didn't come out til 2006, as a 2007 model. Sounds like it's a good match for the boat! Not sure about your 2005 model, but the OPTIMUM WOT rpm for the 2008 models was 5500-5600, so you're definitely overpropped if it only turns 5300. What prop are you currently running? Assuming your motor height is right and AV plate is dry when you're fully trimmed out on plane, I suspect you'd like the motor even more with a prop that has a little less pitch! You might check out the E-Tec Owners web site, http://www.etecownersgroup.com/post/...-Chart-2671224, and post current prop dimensions and performance info to see what they recommend for the best prop. The Rebel seems to be the favorite of the guys running heavy deep-V's for best fuel economy, good stern lift and ability hang on plane at low speed. Sort of like a 4-blade but without the drag of the extra blade.

Pair of Jacks, I notice the 200 HP small block OPTIMUM rpm is 5600- 5850, which confirms my suspicion that it's optimized for max HP rather than mid-range torque. If you're only turning a 14.5 X 15P to 5400 rpm with a light load, going up in diameter is probably the wrong direction unless that's a really lousy aluminum prop. Your 175 should be turning about 5600 with a light load. I would think the 15.75 x 15p Rebel would be even harder to turn. I can turn a 4B 15x15 PowerTech ELE series prop about 5400-5500 on my 20. but not sure that larger diameter Rebel would be any easier to turn, even with one less blade. Here's a link to the BRP props http://www.etecownersgroup.com/post/...-Chart-2671224. You might also contact PowerTech http://www.ptpropeller.com/content-c..._90_300hp.html to see what they recommend. They make some very nice USA-made props at very competitive prices. My prop is compatible with the Michigan 2-piece hub system which appears to be significantly more robust than the Merc Flo-Torq hubs I've looked at.

I would buy the 200 hpdi. Bulletproof!

All things being equal, a prop of greater diameter would be harder to turn because it has to displace more water. In turn you get lower rpms.

Being that you are talking about 2 different props of different shapes and maybe materials, it is possible that with less cupping and moderate rake a wider wheel could give you more rpm than what you currently get. There are SO many prop designs.

Svc mgr sounds like a salesman. In theory "better grip, reduces slip" if you have enough power. So it doesn't really increase power, but rather, requires more power as the prop is "holding" more water. "Power" is what you're about 400 rpms short on. If I'm not mistaken, your etec would be be happier if able to get 5800 rpms with your tyipical full load.

Pitch is in theory how far a prop moves in 1 rotation. The prop's cup, rake, & shape and the hull and its power work together to screw up the theory. The result is slip. So pitch is not necessarily interchangeable as svc. mgr suggested.

An 1-1/4" of diameter is significant. I would not drop 500 clams on the marina managers suggestion. Said Rebel might be the perfect prop but if he's so sure, ask him to loan you one.

In general, you need a stern lifting prop that is easy to turn. I don't know specifically the BRP products that offer that attribute, but Bushwacker or someone on the etec board might. PowerTech is making some fine props at very good prices. I would look at the MQS 3 blade ,the SCE and the ELE series. The MQS and SCE are proven stern-lifters. Maybe Bushwacker can offer more insight on the ELE series. Mercury's Mirage plus and Old OMC SSTs also have a strong following among SeaCraft owners on this board.

Looking at the Vipers performance on the Dusky, that might be worth learning more about. Keep in mind that such a performance does not necessarily translate to the SeaCraft hull.