|
Seafari 25 performance
Well, I finally got my new (to me) boat back from the mechanic. Looks like the work was done well, but it took a loooonnnggg time. First time out today and I did a bunch of performance testing, results below. You guys who are familiar with vacuum gauges, please look at my results and tell me what you think. I'm particularly interested in using it to help establish the most efficient cruising speed. (sorry for the rough tables, I can't get this program to work quite right)
The boat is a near original 1972 25 seafari with a 1998 fuel injected 5.7GSI volvo/volvo sx duoprop. aluminum D2 props that were somewhat nicked when I started and are a lot nicked now. Somebody put a sand bar where it wasn't supposed to be. The grounding only affected the fuel economy estimate and probably not much of that. I suspected the boat was underproped. It is. max rpm is 5100, 100 over the max. My old Seabird 24, about the same weight,carborated 5.7/290 duoprop with F5 stainless props, was right on red line for that engine, 4600 rpm. This engine has a 4600-5000 max rpm range. If I go to stainless props that drop the rpm to 4800, do you think I will gain a knot or two and fuel economy to get near 2.9 npg from the current 2.6? Conditions, 15 knots out of the NW, long fetch in a shallow bay and a short, breaking 1-2 ft chop, the kind I like to call "washboard" Not a major test for the hull, but I could run straight into it at 28 knots and still be comfortable. No pounding, the hull just got jittery sometimes. My old seabird would have been rattling my teeth at anywhere near that speed. General impression: I'm going to like this boat. It obviously is going to live up to its rep as a sea boat. Its tippy, much more so that my seabird, but no worse than a formula 23. It is very lively at rest, I think more weight will help that as it settles down on its lines. Did not see a snap roll like a formula, but the conditions were not a fair test. Too early to tell on roll. Just looking at the hull, it doesn't have the appearance of a dry boat, but I ran around for 3 hours on a day that should have produced a fair amount of spray and had almost entirely dry decks and very little spray on the windshield, not a complete test, but looks good. 24 mile economy run, 2.6 npg Half way through, props very nicked. One person, full load of fuel, 3300 rpm. Can anyone tell me what is the most efficient rpm for a fuel injected engine? hole shot: just over 2 seconds All other speed/vacuum data taken with one person, 1/2 load of fuel NO LOAD, OUT OF GEAR, WARMING UP RPM Vacuum 500 13 1000 16 1500 19.5 2000 20 2500 20 3000 11 3200 9 3600 3800 6 4000 4 Under LOAD falls off a plane below 2400 if tabs and drive are not down. Minimum planing speed, 12 knots at 2200.. RPM Speed Vacuum 2200 2200 --12.2, tabs down 2400 --14.4 tabs down 2400 --13.2 tabs up 2600 --15.7 2800 --18.3 3000 --21 --12 3200 --23.6 --10.5 3400 --26 --9 3600 --28.2 --9 3800 --30.2 3900 -------7 4000 -------6 4200 -------5 4350 -------4 |
Re: Seafari 25 performance
Sweet! Congrats! Gets some pics up. Nice report. I think you'll be right on target with your stainless decision. I'm a bit curious myself. I'm sure Bushwacker will chime in re. vacuum. If I'm not mistaken he's a proponent of such measurement to maximize performance and warn of impending doom :D
Impressive min. planing speed... Your economy on the seafaring hulk is impressive, too - if you can pull 3mpg out of her I'll be upgrading sooner than I suspected. Love to hear more about rock and roll troll and drifting or sitting in swells. I'm not familiar with variability of prop geometry on duoprops so your experience will be enlightening... please keep us posted.:cool: PS you didn't buy the one in LA did you? |
Re: Seafari 25 performance
I got lucky. This one was close to home, in Palm Beach Gardens.
|
Re: Seafari 25 performance
Cool!! The lack of spray doesn't suprise me. I like that 12 knot min planing speed also. That comes in handy offshore.
|
Re: Seafari 25 performance
Offhand I'd say that's pretty good performance for a hull with that much deadrise with a set of nicked up props! Very impressive that you can plane at 12 mph, as many boats with 25 degrees of deadrise can't do that! I always thought that hull might need a big block engine for good performance, but that small block/duoprop setup is lighter and very efficient, so it sounds like it's a good match. By the way a friend of mine named Herman Johnson had a Seafari 25 and lived in Palm Beach Gardens - any chance you bought his boat?! We must live pretty close; we ought to get together some time!
I'd take those props to Bobby Soles and ask his advice; he might be able add some more cup to them to get the rpm down. Best to tweak them to determine right dia/pitch before you spend big $ on a stainless set! You might also want to keep that aluminum set, as they sound ideal for heavy loads. As Fr. Frank says, most folks end up over propped because they don't test the boats with the loads they finally end up running! 5100 doesn't sound like a lot of rpm for a small block Chevy, but maybe they're worried about the valve train. Those ball-stud rockers with the pressed in studs are the first thing most guys change when they try to soup up a Chevy. Vacuum numbers with no load on engine aren't particularly meaningful. Main thing is that vacuum is steady at idle; 13" at idle sounds a little low, but that's a function of cam lift, duration and overlap. The fact that vacuum picks up so much at 1000-1500 is further indication of fairly aggressive cam timing. The 5.2L in my truck runs about 19" at about 600 rpm idle, but it's only 235 hp with a very mild stock smog motor cam. The only comparison I can give you on speed/vacuum is from the "Unohu", a friends old SeaCraft 21 when it had a carbed Mercruiser 350 Chevy/Alpha 1 outdrive. I believe it was rated at about 260 hp with the gear ratio he was running. He used to cruise at 20 kts/~23 mph at about 9" vacuum (with very heavy Bahamas-cruising type load), and I believe top end was around 45-47 mph; used to average about 2.5 mpg. I think you're doing quite a bit better than that! He later had a carbed Volvo (non-duoprop)/350 Chev in it rated at 270 hp, and he claimed it would run 50 mph, but I believe it was jetted richer and he indicated he lost some mpg. Regarding optimum cruise rpm, IC engines are generally most efficient, as indicated by minimum specific fuel consumption (fuel flow/HP), at the point of maximum torque. If you can find out the max torque/rpm rating that would be a starting point. Maximum mpg of the installed engine/outdrive is a little different and involves a lot more variables. Installing a flowmeter is the best way to nail down optimum cruise settings; the modern systems that combine speed with fuel flow with speed will calculate instantaneous mpg and can even help you optimize engine trim and trim tab settings, in addition to tracking total fuel burn. The next best way might be to look carefully at the vacuum/speed relationship. I'd suggest plotting vacuum vs. speed and then looking at inflection points on the curve, after you're up on plane. You're looking for the combination of highest speed/highest vacuum. Large speed increases with a small vacuum drop indicates you're in the optimum speed range. When vacuum starts dropping faster than speed is increasing, then you're running faster than optimum. (Caution: this approach is only valid above about 5" vacuum; on most engines the carb or FI system will dramatically increase fuel/air ratio or richen the mixture at or below 5", so you'll see big increases in power and speed for small decreases in vacuum once you get below 5". Part of this increased fuel flow is to help cool the exhaust valves, because lean mixtures burn very hot!) Denny |
Re: Seafari 25 performance
Connor,
Glad to see you got her wet! Your performance numbers are not too far off of mine. Those duoprops got me beat by a few MPH. Pretty much, where you indicate your speed in knots, I get the same in MPH only my max RPM is 4200 @ 32MPH. Running into a chop, I find it best to trim bow all the way down for the most comfortable ride. As far as spray, I usually manipulate the tabs so as not to create any. In really nasty conditions, I may get a little over the rear quarter but I'm not sitting back there. :D If I'm travelling a long distance in those conditions, with passengers back there, I'll put on the rear curtains for a completely dry ride. You've got yourself a nice rig there. ENJOY! Ours is being pulled this week for the winter so the next 6 months are going to be long ones for me... :mad: Brandon |
Re: Seafari 25 performance
Wow Denny, that's fabulous information. Thank you VERY much!
It looks like I can adjust rpm for max efficiency on the fly with a vac gauge, no matter the load. Looks like 9 inches is near the magic number for me too, about 35-3600 with this load. Bahama trips are my main use of the boat and that means about 1000 lb over what I was carrying yesterday. I'm a little surprised the rpm for high efficiency is above 3400. That seems high to me, a lot higher than a carbed 5.7. Is that a function of fuel injection? Maybe that will change with higher load. One more question on vacuum guages: This one is on the end of what must be 25 ft of plastic hose. Does hose length affect reading? The low planing speed hasbeen a huge advantage for me, although with the seafari, I won't need it as much. It is mostly the result of the duoprop, but my seabird would plane down to 11 knots, even with a heavy load. It had very wide tabs, which I liked a lot, and they may have had something to do with the low speed. I really hate the single stick control on the seafari tabs and will be changing to a two button soon. Also maybe wider tabs, when my budget recovers a bit. On props, I will be getting another set, as soon as I figure out what size, and use these as a spare. My wallet howls every time I think about stainless volvo, but I run in shallow water, coral, etc a lot. Think I gotta do it. Has anybody tried putting extra weight, lead, concrete, whatever, way up in the bow of this boat? The engine sits so low, 3-4 inches below what volvo recommends, that I worry about water intrusion, especially with the idiotic volvo placement of the flapper valves inside(inaccessible)the exhaust pipe. You can't tell if they are working or not. Mine were stuck when I bought it. I'm planning to install 2 inch spacers to raise the risers, but when 3 or 4 guys gather in the stern, the boat sits very very deep. Maybe a couple of hundred lbs in the bow would help keep the stern from sinking so far. Might also damp the roll a little. Thanks again. |
Re: Seafari 25 performance
Denny, this was not your buddies boat, but you have probably seen it, pretty distinctive, light blue hull, white topsides and bimini, white fish box built out aft of and across the stern.
Brandon, what width tabs do you have on yours? Connor |
Re: Seafari 25 performance
Hi Connor,
If you're gonna carry another 1000 lbs, which sounds typical of Bahama trips, the props you have may be about right! I had my spare Al prop cupped so that it would turn about same rpm as my stainless prop; when I got over to the Abaco's I would switch my good stainless prop for the aluminum prop to prevent reef rash on my get-home prop! The rpm for peak efficiency is primarily a function of the cam but the amount of gear reduction and prop design will also affect it. A 4 blade prop will sometimes be more efficient at cruise because it has less slippage, but higher friction losses at high rpm tend to hurt top speed. The duoprop may have similar issues, but it should eliminate all the swirl in the prop wash which should be a good thing. Both the diameter and length of the tubing will affect TRANSIENT response of any pressure gage, but since there is no flow going thru the line at steady state conditions, it won't affect the reading. When I first hooked up the vacuum gage in my truck, I tee'd into the vacuum line running to the power brake booster with a 1/4" line about 2' long and that was too sensitive - the gage would fluctuate a couple inches as each cylinder fired! Had to put a .060" dia. orifice in the line to stop that! Sounds like you might want to move those exhaust risers up more than a couple of inches! Having them too low is a quick way to kill an engine! I'd never add weight to a boat just to balance it, but have you considered adding a ballast tank? It would damp roll as well as help adjust longitudinal trim. (Check out Moesly's patent Moesly's Patent on Carla's web site.) He used ballast tanks in the race boats; they worked well and he supposedly designed the Seafari 25 with the idea of using a ballast tank, but sold the company to Potter before he ever built a 25 and Potter evidently never included the ballast tank. Denny |
Re: Seafari 25 performance
I guess a picture is worth a thousand words. This was taken before my cleanup and paint a few years ago.
[image]http://i446.photobucket.com/albums/q...Picture188.jpg[/image] I credit my Grandfather for getting those on. I've never run the boat without the plates on the tabs but they are super sensitive when activated. I usually have a list corrected seconds before the weight shift :D In my younger, crazier, foolish, stupid, stupid, stupid years, usually to impress a young lady...stupid...I would trim port tab all the way down and starboard up and lay the boat on her side, without turning the wheel, at about 20 plus and yell" we're goin over" or some stupid thing like that...anyway my point is, the tabs are effective and...we were all young at some point :D. Ours are made of steel and are holding up but when I have to replace them, I'll try aluminum. Well...I guess I gave you a thousand words anyway :D |
Re: Seafari 25 performance
A thousand words indeed. That pic helped a bunch.
My tabs are a couple of inches narrower and more inboard. Coming from very wide tabs, they don't seem to me to work all that well. I might switch to something closer to yours, but all in good time. Denny, I might have to raise the engine box to get 4 inch extensions in there. Food for thought. I had already looked at the Moesley ballast patent and considered it neat but impractical. I'm rethinking that now after seeing the problem. If I could come up with a bullet proof fill and drain system that was fast, there is room on the keel forward of the seats. Will be doing some calculations on how much weight would be added. Does anybody know how much room there is under the well between the seats at the aft end of the well? Connor |
Re: Seafari 25 performance
Just went out and measured, and I'm pretty sure I can get 4 inch riser extensions in without raising the engine box. that makes me very happy. Also got a chance to try straightening out the props. Boy, did I screw them up! Seems like I do something like this every time I buy a new boat.
Interesting info on props vs load. I will have to get a bunch of people on board and get some more data to see how much relation there is with a duoprop. Duoprops are different in unusual ways. Look at the props and they don't have all that much diameter, even though, with a total of 6 blades, there is a lot of blade surface to grip the water. What really grabs you is the pitch, its huge. They get away with this by turning them real slow. If you are towing behind the boat and look at the props, you can almost see them going around, compared to just a blurr with other drives. Very distinctive. The slow turning speed reduces cavitation and frictional losses, contributing to efficiency. I've read several places that fuel injected engines were using very aggressive valve/cam timing/overlap (not exactly sure of the right terms). Bushwacker's comments about my vac results are consistent with that. It also makes the engine more susceptible to water intrusion via reverse reversion, a real nasty for me, with such a deep engine and since much of my diving is drifting with the divers, at idle where rr is worst, stern into the wind and wave. I like the idea of 4 inch extensions, very much. Connor |
Re: Seafari 25 performance
I'm glad to finally see a dialog about a 25 Seafari. Thanks, Connor, for posting your performance numbers. I have some thoughts, but understand that these are mostly based on investigation and not actual experience, since the only time my 25 has been wet since I bought it was when I left it out in the rain.
Quote:
Quote:
Quote:
Seafari25, the tandem trim tab setup is very cool and an ideal solution for these variable deadrise hulls. What was used as a linkage between the inner and outer tabs? Dave |
Re: Seafari 25 performance
A pic may be worth a thousand words, but you have to actually look at the pic. I totally missed the double tab. That is amazing. Ditto on Blue Herons question. Maybe I can do the same on mine.
Dave, thanks for the measurements. I also was thinking water storage before I thought about Bushwackers comment. If you would like to get together and compare boat notes, let me know. Connor |
Re: Seafari 25 performance
Quote:
You're in Sarasota, right? I'll be going down to Bonita Springs on Wednesday 11/11 and returning Sunday 11/15. I'd love to stop by and see your 25 on the way down or back if that's convenient for you. I've never owned an I/O before and I'd like to get the benefit of your experience. Dave |
Re: Seafari 25 performance
Quote:
The "plates", as I like to call them, are all one piece 3/16 steel, bent the shape of the hull and welded to make a channel in the middle(can be seen right side of port tab, left side of starboard in above pic). The top of the channel is level with the top of the plate. The bottom of channel is level with bottom of plate but the forward edge is bent(curved) upward so it never drops below hull and also seals the channel from the front. The rearward edge of the top of the channel is cut out to allow better access to bolt it to the trim tab. The plates are each secured with 4 1/4" SS bolts. Wow that's hard to explain. That's why I hoped a picture was worth a thousand words.. :D JK...Happy to answer any further questions fellows. Brandon |
Re: Seafari 25 performance
Dave,Come on down!
Either day will work, 11/11 or 11/15. I can definitely be home on the 15th. The 11th is a work day, but its my company, so there is some flexibility. Let me know your schedule and I can almost certainly find a way to make it work, The 13-14 is out. I live close to US41, about 8 miles from the nearest interstate exit. Connor |
Re: Seafari 25 performance
Ok, Brandon, I'm dense. Could you possibly take some closeup pics of those tabs. I promise to look closely at them.
Couple of questions. Do the steel tabs move up and down with the bennet piston? Are they attached to the hull at all or only attached to the bennet tab? If so, they look fairly far off center to the piston. Has that ever caused a problem? Connor |
Re: Seafari 25 performance
Connor
Yes the steel tabs move with the piston and only attached to the bennett tab, no contact with the hull. The steel is sistered to the aluminum each with 4 bolts. As far as I know, Gramps had the plates made while he was chartering the boat in the mid to late 70's on Lake Ontario. He replaced the original joy stick in the 80's with the double rocker still on now and I had the original actuators replaced a few years ago. Other than being upset that they cut holes in my inner transom when installing the actuators :mad:, no problems. Structurally, the steel has held up quite well. I removed the plates about 8 or so years ago and sandblasted them. I had to weld in a small patch on one that I blasted through and I coal tarred them. They'll last a few years yet but I think I might try making them out of aluminum next time. I'm hoping the boat is out of the water by now and I'm planning to hit the cottage this weekend to pull the docks. My good camera crapped out but I'll try to get some close ups with the blackberry and get them up before she goes to hibernate for the winter. Brandon |
Re: Seafari 25 performance
When I repowered a couple years back, I had the four inch extensions on my engine. I looked at several boats and they all had them (of couse mine is a inboard).
|
Re: Seafari 25 performance
Riser extensions will go on the boat in the next couple of months when I change manifolds, 4 inch for sure, maybe 6.
Made another discovery, there was something blocking the throttle lever and removing it increased the WOT rpm to 5200 with one person and a full load of fuel. Had a bunch of people on the boat today, 4 adults, 2 kids and 150 lb of ballast forward. Not quite a Bahama load, but reasonably close. Re-ran some vacuum, rpm, speed data (see below) and found some interesting stuff. Putting the extra (~800lb) load in the boat dropped the speed in the 3000-4000 rpm range by right at 1 knot. The most efficient rpm dropped from 3400+ to 3200, roughly. Max rpm dropped about 150rpm with the increased load, 5050rpm heavy, 38.3 knots. I discovered that the most efficient cruise and amount of vacuum was highly dependent on the amount of tab and drive trim, which I had not been paying close attention to. To really dial in most efficient cruise, I will have to fix the trim indicator so I know exactly how much trim is on the boat and get a better tab system(the tab part is coming, soon). I did not have time to rerun the fuel economy, but my guess is it dropped to 2.4-2.5 nmg. Previous comments about this hull needing weight to run right and Carl M's original plan to put a water ballast system in this hull seem right on target. The boat is so sharp and narrow in the forward sections that there is very little beam in the water. The chines at the transom are barely in the water when it is very light. Adding some ballast forward made a noticable diffence in how lively the boat was when at "rest" Putting a heavy load in it did not change how it handled when moving(at least, not much), but improved it when at "rest" or going slow. The roll was much less "quick" Data with heavy load rpm a------- vacuum---------knots 3000-----------10.1---------19.2 3200-----------10-----------22.6 3400-----------9------------25.1 3600-----------8------------27.1 3800-----------7------------29.5 Max rpm full fuel, one person 5200 max rpm with above + 800 lb 5050 38.3 knots Connor |
Re: Seafari 25 Performance
Connor
I saw Carl at the OFF2009 Raceboat gathering and specifically asked him about how much water ballast would be appropriate for your boat. He said Potter didn't build the boat the way he designed it, and that he wouldn't bother with the ballast tank. Your observations are interesting though. Sounds like placing gear as far forward and as low as possible would be worth playing with. Did you get those props fixed? Sounds like you could go to higher pitch, now that you found that earlier run did not get to full WOT! I think that vacuum gage will help you find the "sweet spot" combination of optimum throttle/drive/tab trim. Keep us posted on what you find out! Denny |
Re: Seafari 25 Performance
Well, she was on a trailer awaiting cleaning and winterizing so I got a few shots.[image]http://http://i446.photobucket.com/albums/q...91023-1826.jpg[/image] [image]http://i446.photobucket.com/albums/q...91023-1822.jpg[/image] [image]http://i446.photobucket.com/albums/q...91023-1821.jpg[/image] [image]http://i446.photobucket.com/albums/q...91023-1820.jpg[/image] [image]http://i446.photobucket.com/albums/q...91023-1822.jpg[/image] [image]http://i446.photobucket.com/albums/q...91023-1824.jpg[/image]
|
Re: Seafari 25 Performance
Connor,Here is a pic showing risers per your PM [image]http://http://i446.photobucket.com/albums/q...90920-1917.jpg[/image]
|
Re: Seafari 25 Performance
Outstanding pics! Just what I needed to show the welder.
Thanks Connor |
Re: Seafari 25 Performance
Brandon-
Interesting that your boat's scuppers are in the stern while mine are a foot or so forward of the stern in the sides of the hull. strick |
Re: Seafari 25 Performance
Mine are where Brandon's seem to be. They exit through the side of the boat. Much of the time the deck tilts slightly down going forward, so scuppers more forward sound like a good idea.
Brandon,thanks again for the tab idea. Those are even larger than what I had on the Seabird. Looks like there is enough surface area to damp the roll quite a lot. I'll find out. Denny, that vacuum gauge is the cats meow. You have made a convert. Haven't fixed the props yet, but I think I know what I want. Same engine F5s(stainless) was 4600 rpm in the Seabird. These are D2s (aluminum) and turn 5050 loaded. The volvo book says 200-250 rpm for each size larger in duoprops and go one size larger for equivalent in stainless. That gives me a F4 which should give about 4800 loaded. Max rpm range 4600-5000 on this engine. I'll have several conversations with prop guys first, but thats what I think for now. Does being in the middle of the max rpm range with the boat loaded close to the max its likely to carry make the most sense? One thing I don't understand, maybe someone can shed a light. The volvo book says most efficient cruise speed is 15-25 percent below max speed at max rpm. That results in real high rpm that the vacuum gauge says is too high and looks too high to me as well. Any comments? Connor |
Re: Seafari 25 Performance
Strick,
It is interesting about the different scupper locations. I think Nuthinfancy's are even more forward of yours. I guess the ones that were set up with the huge twin engine box the full length of beam would've had to have had them farther forward. Quote:
At rest, with no passengers, ours drains towards the transom. With two in the cabin, it drains forward then back then forward....JK it drains forward then I go to sleep :D Enjoy the new tabs Brandon aka WTMFI guy |
Re: Seafari 25 Performance
Quote:
I'd get those aluminum props fixed and run them again before making a final decision on SS props. As for rpm at Max load, being at the middle of the range is probably pretty close. High end of the range is probably easier on the engine, low end may give a little better mpg, so splitting the difference is a reasonable compromise. I know Fr. Frank says to prop for Max rpm at Max load. I'm sure that's true for 2S outboards that run needle bearings, have no valve train to worry about, and love to rev. Lugging an engine (high load at low speed) increases cylinder pressures and temperatures, which increase loads on pistons, rings, bearings and valves while the low speed REDUCES oil/coolant flow and pressure, so it's generally better to let 'em rev! It's probably true for 4 strokes as well, but they can have valve train issues (resonant vibration that can wear or even break valve springs, dampers, studs and rocker arms if you spend much time at a critical speed). 200 rpm isn't a big deal, but I'd try to find a Volvo engineer, and ask him if you should prop it for 4600 or 5000 at max load, and why. If there is a critical speed, say 5100-5200 you'd like to know that too! [/QUOTE]One thing I don't understand, maybe someone can shed a light. The volvo book says most efficient cruise speed is 15-25 percent below max speed at max rpm. That results in real high rpm that the vacuum gauge says is too high and looks too high to me as well. Any comments? [/QUOTE] That 15-25% recommendation is a very general statement and not necessarily right for a specific boat. It should probably say MAXIMUM cruise rpm, not the most efficient speed! You're right, the vacuum gage is a much better indicator of best efficiency, and I'd guess 3750-4250 rpm is pretty close to 5-7" vacuum or max continuous power for that engine, if it had such a rating. If you're gonna take that boat to the Bahamas, you'll be burning enough gas that I'd spend the money up front to get either a Floscan system or the Volvo equivalent of the I-Command/Smartcraft system if there is one. It'll eventually pay for itself by helping you to always run the boat at optimum trim, plus it's good to know exactly how much fuel you've got left and not have to depend on a gas gage that may not be very accurate! |
Re: Seafari 25 Performance
Quote:
strick |
Re: Seafari 25 Performance
yeah mine was origionally a twin sterndrive and had the huge box. and my scuppers are almost directly below the shorepower plug, inline with the bulkhead between the engine compartment and fuel tanks, almost directly below the end of the side windshield
|
Re: Seafari 25 performance
Quote:
Sorry it took so long to reply. Work and family obligations have been kinda intense over the past week. The 15th works better for me too. If it works for you, I'll plan on leaving Bonita Springs 9ish and see you around 11:00. I'll PM you my contact info so we can communicate off the thread. Dave |
Re: Seafari 25 performance
Much work done, now the testing begins
New Bimini, stainless F3 props, dive platform, 8hp hi thrust Yamaha kicker, lots of cabinetry. Now lets see what it will do. First the kicker. Very pleased. I'm still breaking it in and only ran up to 3/4 throttle, was getting 4.6 kts in calm water and 4.0 into a steep chop and 15 knots of wind. My old 15 hp on a 24 Seabird would do no more than 4 knots in flat water and practically nothing against wind and chop. Further, the Yamaha has full control of the boat even into that chop. I plan to use it as a trolling motor, follow the divers, etc, which should cut my fuel consumption considerable. New props dropped the max rpm from 5200 to 5000 with a light load (full fuel and one person) That's right at the top of the recommended rpm range for this engine. I talked extensively to a prop guy and decided to go with less pitch than I originally wanted. Think I got it just about right. Found the props used, like new, on Craigslist. Platform is outstanding. I had it built to include a big box (5.8 ft x 1 x 1) for storage of freediving gear. This takes care of the only real drawback in the Seafari, lack of gear/fish storage. One negative, we made the box lids a little too close to the transom rub rail and I had to mount the platform a couple of inches lower than planned. That may require some modification down the road. Looks like max efficiency based on the vac gauge is 3200-3300. I did a 15 mile mpg run and must have messed up somewhere, got 2.3 nautical mpg. Will redo that. Boat speed (and mpg) seem very sensitive to tab and trim. Lots to learn on how to tweek it. Speed at a given rpm with the new props picked up about 3.5 knots in the 3200-3400 range. Looks like 27-28 knots at 3300. That will drop some with a heavy load, not sure how much. Did not write down the max speed, but I think 44 knots. Here is a funny one, maybe somebody can shed some light. I have two gps units. the one that came with the boat (all data above) and a hand held Garmin 76 off my old boat. The two give quite different speeds, 7-8 percent off, with the Garmin giving slower speeds. Makes quite a difference at 25 knots. Anybody know why? And I promise, really, to take a bunch of pics this weekend and try to figure out how to post them. Thanks to all for your help. Connor |
Re: Seafari 25 performance
Quote:
|
Re: Seafari 25 performance
Yeah, I was thinking that too. I hope I'm wrong because 44 knots is phenomenal but maybe it IS reading in MPH or we even have kilometers per hour or our gps's up here :D
Ken Kurek told me he gets 44 kts with his 454 so if you're getting it with your 350.....I want one...and the duoprop...but I'll still probably go 4 knots :D Thanks for sharing the numbers Connor. If you would like, send me your pics and I'll post them Brandon |
Re: Seafari 25 performance
Quote:
|
Re: Seafari 25 performance
Thanks for the tip, you guys were right. I never thought to look, but the previous owner had set the unit to read statue miles. I fixed it and will redo some runs to make sure, but it looks like max speed drops to 38+ knots with max efficiency around 24 knots at 3300. Looks like the Seafari will be slightly slower(2 knots?)at cruise than my old Seabird and not quite as fuel efficient, but the totality of the numbers, bigger, deeper boat, etc, look much more likely.
|
Re: Seafari 25 performance
Quote:
Connor- I can host your pictures as well. I have my own web server...just e mail either of us some pictures!!!!!! :D strick |
Re: Seafari 25 performance
Strick,
I sense a bit of Pavlov's dog out there. Keep the napkin handy! :D :D |
Re: Seafari 25 performance
Quote:
strick |
| All times are GMT -4. The time now is 01:23 AM. |
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2025, vBulletin Solutions, Inc.
All original content © 2003-2013 ClassicSeacraft