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Newfie on your boat
Swabbie
Canada
5 Posts |
 Posted - 02/14/2010 : 19:11:28
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Hello All,
I have a 1976 Pacemaker Sedan Bridge 30 foot, and Love it. I have rebuilt the engines, carbs, the whole nine yards. engines run great, but I can only get 3200 rpm and 17 knots out of the boat. I can not get up on plane, and run like the one other Pacemaker in this area. The Manual states that i should be able to runn at 4400 rpm and 30 knots. the Propellers that are on the boat right now are 3 blade 10 x 14. These props have been changed out by previous owner. Any suggestions?
Newfie on your Boat |
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Rich P
Administrator
USA
276 Posts |
Posted - 02/14/2010 : 19:51:15
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Welcome aboard.
Are the distributors advancing? How clean is the bottom? How much extra "ballast" has the boat acquired over the years? Do you have trim tabs? DO you know what the original props were? |
36' Sportfish
Eastern Long Island, NY |
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Newfie on your boat
Swabbie
Canada
5 Posts |
Posted - 02/15/2010 : 17:20:04
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HELLO Rich,
The distridutors are advancing like they should. The bottom of my boat is very clean, i am a diver so i clean the bottom about once a month. When i was running my tests the boat was bare bones (besides a few cold ones of course back at the dock). i do have trim tabs but do not use them very much.. they do not seem to change anything. as for the old propellers that is what i am tring to find out. All that i have found so far is that the should be 4 blade 13 x13 1 inch bore Michigan Wheel. Not 3 blade 10 x14 1 inch bore which is whats on her now. |
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Rich P
Administrator
USA
276 Posts |
Posted - 02/15/2010 : 20:21:23
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| Where did you get the 4 blade 13x13 dimention? If you don't have the original paperwork from Pacemaker, see if Commodore Dewey has them. I found some interesting reading from my original paperwork. See the "Urgent: Pacemaker FIles" |
36' Sportfish
Eastern Long Island, NY |
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joebobb
Forum Admin
USA
442 Posts |
Posted - 02/16/2010 : 14:39:53
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Hello Newfie,
Seems puzzling, because your results seem to be logically conflicting. The 10x14, 3-blade props should be much easier to turn than the 13x13 4-blade props. I haven't done the math, but in terms of blade area they should be substantially smaller. The one degree of additional pitch counteracts this to some extent, but I can't imagine that it would offset the impact of the diameter reduction and the reduced blade count. So I can understand the loss in boat speed but it seems to me that the engines should be able to spin the hell out of these smaller wheels. Thus, the low rpm at WOT doesn't seem right. Two ideas...
1) Verify that the throttles are opening all the way at WOT. Could be a cable adjustment/travel problem that is artificially limiting the engines' WOT rpm.
2) A crazy thought, but are you sure the transmissions are correct for the engine/prop/boat combination? If someone changed the props, it's possible that they also changed the transmissions - possibly changing the reduction ratio in the process. Maybe a previous user put in a couple tranny's with steep gearing in the boat (for whatever reason). It could be that the radically different props were actually an attempt to offset the impact of this modification?
Kind regards,
JoeBobb |
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Newfie on your boat
Swabbie
Canada
5 Posts |
Posted - 02/22/2010 : 14:27:14
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Hello All,
Thanks for all in leads, I found all the orginal paperwork for this boat and the Porp size is 14 x 11 3 blade. I got the 4 blade from Iboat website when you type in the boat and engine it gives you the props it told be 4 blade prop. I have check the transmission and the throttles ( Thanks Joe) the transmission are 1:1 ratio which is what they are meant to be. the the throttles open about 95% of what they should ( new cables and throttles maybe needed). the props are now gone to a Prop dealer and he is fixing them up. I have also order a new trim tab pump. i will let you know how I make out in the spring with the next set of sea trials. thanks again for the help. |
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Rich P
Administrator
USA
276 Posts |
Posted - 02/22/2010 : 23:10:44
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| 1:1 ratio seems a bit odd to me. What engines do you have? |
36' Sportfish
Eastern Long Island, NY |
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changeofpace
OLD SALT
340 Posts |
Posted - 02/23/2010 : 19:53:56
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| Rich, I have 1:1 velvet drives on my 74 hooked to twin 350's. The specs on my engines list the timing at 4000 rpm, which you cant set unless your timing light has the adjustment on the back. Here is an easy test but requires 2 people to do. Bring the boat out, bring her up to WOT, then have someone very slowly advance the timing and see if the rpm goes up. If the engine is advanced too far, you'll hear and feel it. Same as being retarded too far. Once you have reached max rpm output, tighten the bolt to lock the distributor. You should then check the carbs and for vacuum leaks at the base of the carb. Cant help you with the carbs as I have the mechanic set mine up, To check for leaks, while at the dock and at idle, spray water around the base of the carb. If there is a leak, the engine will pick up speed. If everything checks out engine wise, you need to check the transmission for wear in the disks causing them to slip robbing the boat of speed |
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joebobb
Forum Admin
USA
442 Posts |
Posted - 02/25/2010 : 15:03:08
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Newfie, I don't think the 1:1 transmissions are correct for your boat. The Pacemaker documentation I have shows 1:1 drives for the twin gas V8 28-footer's (like ChangeofPace's boat), but for the 31-footer and the 33-footer (sorry, I don't have any information for the Pacemaker 30-footer) the documentation I have shows 1.57:1 trannys for the 31' and 2:1 trannys for the 33' (both with twin 250HP small-block Chevy's). Due to the manner in which volume and displacement increase to the cube per foot of length, I would expect the 30' to be closer to the 31' than the 28' in terms of displacement, power requirements, etc.
I think my original comment above is worth of looking into. It could be that someone did a tranny and prop swap at one point in time. Actually, what is very likely (you haven't mentioned if the engines were original) is that at some point in time a former owner swapped out the original engines/transmission for a matched pair (probably used) he got for a good price. The new transmissions were 1:1 - he (and maybe his less than competent mechanic) figured they could compensate for the transmission difference with a propeller change.
I really have a hard time believing the 1:1 transmission are correct for that boat with the 14x11 wheels. My boat (a 25') with the single v8, a 1:1, and a 13x10 is well matched (the engine turns 4800rpm at WOT - pretty much right on the money). However, on a heavier boat (like yours) with a bigger wheel with more pitch (like the 14x11) there's no way the same engine is going to be able to reach the same rpm. The results you are seeing with the current 13x13 seem logical to me in this scenario...the engines are being over-taxed by the combination of the 1:1 direct drive (too high a gear) given the additional displacement and the additional prop pitch.
Kind regards,
JoeBobb
PS: I would recommend that you continue to research the original set-up for your boat. I don't know exactly how to find this out. Hopefully you'll get some more replies here. You can also do a search of the website for "30" and/or a few other key words (or just browse through some threads) and find a couple owners with 30-footers. Send them an e-mail directly using the site's e-mail function.
Alternately, there are probably some books or magazines that might have this information. Maybe you can go to a library and see if it's possible to find archives of old boating magazines from this time period. You can probably find a review of your boat somewhere. Another option: in the "Links" section of this site there is a company with an eBay store that sells lots of old boating magazines, articles, and advertising materials. Check them out or send them an e-mail describing what you want. |
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joebobb
Forum Admin
USA
442 Posts |
Posted - 02/25/2010 : 15:14:34
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Newfie - go to the search function, type in "30 foot" (leave out the quotation marks), click the radio button for "match exact phrase" and you will see a bunch of threads where someone with a 30-foot boat posted a comment. You might find someone who states openly what their prop and transmissions are. Otherwise, you can send them direct e-mails.
Kind regards,
JoeBobb |
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Paul Nasto
Captain
USA
96 Posts |
Posted - 03/01/2010 : 22:46:21
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| I have a 32 s.b im runing 16x16 3 blade props i run at at 18 mph at 3200rpms 4400wot at 26mph i tried 14x14 but was way to small hope this helps |
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Barry T
Swabbie
Canada
5 Posts |
Posted - 03/07/2010 : 17:40:26
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| I have a 26ft Pacemaker with a 318 with a 1:1 transmission, I`m running a 13X10 3 blade RH on a 1 in shaft. The question I have is would it be more fuel efficent to change over to a 4 blade prop or possibly change up to a larger prop. I would like to find a way to decrease my fuel consumption - any suggestions ? Would anyone know what prop was installed at the factory ? There are quite a few similar boats to mine in the area and they all have larger props - Thanks ! |
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Rich P
Administrator
USA
276 Posts |
Posted - 03/07/2010 : 22:13:27
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| What is your engine running RPM wise? |
36' Sportfish
Eastern Long Island, NY |
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Barry T
Swabbie
Canada
5 Posts |
Posted - 03/08/2010 : 11:57:25
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| I can get it up to 4000 - 4200 but that is the top end - I`ve never really compared RPM vs MPH. I don`t usually run it wide open I keep it around 2500 because getting there is half the fun - Thanks ! |
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joebobb
Forum Admin
USA
442 Posts |
Posted - 03/08/2010 : 14:19:11
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Hi Barry,
That's a goal I think we all share. I've spoken to Michigan Wheel distributors in Florida about changing propellers (going to a 4-blade, etc). No one seems to think the difference in efficiency (if any) will offset the additional cost of the new propeller). There was a guy who put a reduction transmission in his boat and a considerably larger prop and he seemed to be getting marginally better economy - but again - was it enough to offset the cost of a new transmission, new prop, etc.? Probably not.
I don't think there's really anything that can be done to dramatically improve fuel economy - at least enough to offset the cost of implementation.
The best option for all of us I think is to a) keep the bottom in good condition, b) keep the engine in proper tune, c) make sure the prop is really spotless and in excellent condition, d) keep weight to a minimum (including fuel), and e) pay attention to weight distribution in the boat...maybe even going so far as to experiment with changes in distribution to note their effects, if any, on performance.
Kind regards,
JoeBobb |
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Barry T
Swabbie
Canada
5 Posts |
Posted - 03/09/2010 : 13:51:43
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Hi Joe,
Thanks I guess we are all trying to get the best fuel economy possible but I do keep the hull clean and tune ups in check, perhaps weight distribution should be looked at - Yours Truly |
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Topic |
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Propeller Size
