| Author | Message | ||
     Jim in Houston Unregistered guest Rating: N/A |
I own a 1982 S2 9.2 with a Yanmar 2GM engine. When I bought it last year, it had a Martec 2 blade 14x14 folding prop on it and was very competative in club racing. This year, one blade broke off and I had to install the old 3 blade 14x8 fixed blade prop while I dealt with Martec. The boat is noticably slower both under sail and under power. I have to pay a 6 second per NM penalty for using the folding prop but it seems well worth it. I can't wait to get the Martec prop back on the boat. Martec denied any responsibility for the failure, but did completely refurbish the hub and installed two new blades for their standard price. | ||
| Jeff Roy New member Username: Jeffr Post Number: 102 Registered: 03-2001 Rating: N/A |
Just want to follow up now that I have had a chance to see how the rebladed prop worked out. It is amazingly better. The very first time I put her in gear with the new 15X12 prop I was impressed with how much more thrust there was and how quickly she accelerated. I have picked up about a knot more speed in all conditions under power. I can cruise comfortably at 6.2-6.4 at about 2800 RPM. At 3000 I get almost 6.8. (I used to be at 5.2 and 5.8 at these revs) I recently went on a weekend cruise and had no wind on one leg and motored for 4 hours. The water was like glass and I was doing 6.8 to 7.2 most of the time. I also noticed the boat does not loose speed as easily when it hits waves and has more braking power when thrown in reverse. I still have more vibration than I would like but am convinced it has to be the engine alignment, which I can never seem to find the time to fix. | ||
| Brad Stone New member Username: Bstone Post Number: 10 Registered: 06-2004 Rating: N/A |
Good points, Scott... Jeff and I seem to have the same 2.6 reduction gear. I'd suggest to anyone thinking of a Martec to go to their site and obtain all the info and measurements they request, including the transmission type and reduction gear numbers... and then give them a call. They are most helpful, and this assures the best match. | ||
| Scott Corder Moderator Username: Scott_corder Post Number: 10 Registered: 01-2005 Rating: N/A |
I am finding these recent posts very informative! I don't have much to add but want to reiterate something I posted a long time ago (a copy/paste of that follows): If you read a post I made much earlier in this same thread on the bulletin board, I mentioned some very strict advice I received from Martec concerning matching prop pitch to the gearbox on the engine. To reiterate: Martec was adamant that the prop be properly matched to each specific Yanmar gearbox to generate maximum thrust at approx 2900 rpm. Anything different and they said bad things could (would) happen (clutch burn out, engine damage, etc.) They also indicated that Yanmar shipped 2GMs with several different gearboxes on a totally unpredictable basis (just whatever gearbox they happened to have on the shelf as they made each engine). This, they said, obviously prevented them from providing any kind of widely applicable formula for prop size and pitch on a Yanmar 2GM. +++ This being said, recent findings seeem valuable but we should remain mindful of the gearbox issues. | ||
| Brad Stone New member Username: Bstone Post Number: 9 Registered: 06-2004 Rating: N/A |
Jeff - After reading your post I gave Martec a call, and here's what they said: Seems the main thing is to get the right thrust for the engine at proper rpm's. Either the 14x14 or the 15x12 will accomplish this. They said they'd always prefer to go with more diameter, as it "grabs" a wider area of water, which promotes better gas mileage - that's the only difference they sighted. The mileage improvement between a 14 and a 15 would be marginal... between a 14 and a 16 would be more noticeable. They're preference on the 9.1 would be a 16x... but there's no room for that on our boats. The mileage on these diesels is pretty amazing in any event! One of their "guidelines" (you probably went through this) is for a clearance of 15% of the prop diameter, between top of blade and hull. I figured this last year when I purchased, and I'm about there. They suggested that perhaps your prop shaft was a bit longer, giving you more room to the hull. They then said that the 15% was "a guideline," and that less clearance has been successful as well. All in all, sounds like six of one, half dozen of another. I had no problems for the short time I was out last year - I'll pay more attention to performance when I get out this year, and post. | ||
| Jeff Roy New member Username: Jeffr Post Number: 100 Registered: 03-2001 Rating: N/A |
Interesting, when I first contacted them they said they would use 14X14 blades, but then called back and said they decided 15X12 would be better. | ||
| Brad Stone New member Username: Bstone Post Number: 8 Registered: 06-2004 Rating: N/A |
My two cents... When I bought my boat last year it had a fixed two blade, so I called Martec for a new folding prop. I have the 2.6 gear also - After giving them all the measurements they specified a 14 x 14 for me. Hmmmm. I can't give specifics on rpm's/knots, cause the boat was only in the water a short time, but I'll add that when I find out this year. | ||
| Jeff Roy New member Username: Jeffr Post Number: 99 Registered: 03-2001 Rating: N/A |
I sent my Martec RH14X10 prop back for refurbishing. I provided all the information they requested and they told me I was "way underpropped" and they seemed very familiar with S2 9.1s and said most of them had the wrong prop. They told me that the earlier Yanmar 2GMs had a 2.1 reduction gear and that is what S2 speced the prop for. Later models got a 2.6 reduction gear and S2 never updated the props they were installing. I just got it back fitted with new 15X12 blades installed on my rebuilt hub. It looks brand new. I will report back when I get it in the water and evaluate the performance. I have never had good performance under power. I could easily over rev the engine and in tough conditions could not get much for speed. Last fall I had to motor into a 35 knot wind and even with the engine at 3400 RPM we couldn't make 3 knots. In flat water I could only reach about 6.2 with the engine reving at 3200, and the slightes wave or rudder movement the speed would drop to 5.8. Under most conditions I motored at 5.2. I would expect these boats to be able to steam at 6.5 or so. | ||
| Mike Bergmann Unregistered guest Rating: N/A |
Another update on the Varifold prop - I came through NY Harbor yesterday with 15 to 20 knots headwind and short chop from tugboat traffic up to 3 ft. I was able to maintain 6.3 knots at 3000 rpm with the new prop - under similar conditions with the Martec I would be lucky to maintain 5 knots. | ||
| Mike Bergmann Unregistered guest Rating: N/A |
Just to update on my new Varifold prop: I did question the Varifold people about the pitch of the new prop before I ordered it. I thought a 15 x 10 would be better than 15 x 9. Varifold told me that the 15 x 9 would give me 6.4 knots +- at 2900 rpm. When I delivered from the winter yard to my summer mooring, I got that speed at that rpm while towing an inflatable dinghy in the worst possible location. I guess their estimate was pretty good. I delivered to a regatta last weekend (25 nm each way) - the new prop gives me 6.6 to 6.7 knots at 3000 rpm in flat water with a 12 to 15 knot headwind. There is reserve for chop. Vibration is nil. This installation is the smoothest I have ever had on this boat - I highly recommend it to anyone who wants better performance than they are getting now. If you want to get more info on this, their web site is www.varipropusa.com, and they can be e-mailed at varipropusa@rivnet.net. | ||
| Mike Bergmann Unregistered guest Rating: N/A |
I have just installed a 15 x 9 Varifold prop (geared folder) replacing my old Martec 14 x 10. The boat is not in the water yet, so I can't report on performance. One warning for anyone changing props: Check the clearance between the prop hub and the aft side of the strut. You need at least 1/4 inch (1/2 is better) so that water can flow through the cutlass bearing. You also need some clearance because the engine mounts will flex under full power and the entire drive train will displace forward due to prop thrust. If you are buying a new prop, try to measure the distance between the forward end of the hub and the seating surface for the prop nut. If the new one is longer than the old one, you may have to do what I did: when I installed the new prop, I had 1/16 inch between the prop and the strut. Varifold confirmed that this was not enough. I ended up buying and installing a "Drive-Saver" which adds 1" to the length of the shaft. Everything is fine, but the "Drive-Saver" is not cheap. I will let everyone know how the new prop performs. The blades are wider than on the Martec, and I expect much better performance in chop and in reverse. | ||
| Brayden Woods New member Username: Brayden Post Number: 4 Registered: 05-2003 Rating: N/A |
Just an update. The decision was to go to the regata "as-Is", and just deal with the engine there. Thankfully the transmission decided to co-operate 80% of the time so we were fine, and while we were slow getting out to the course a few times – it didn't think it effected our performance or enjoyment at all. We decided that we will fix the engine at the end of the season, we were chugging along at only 1500 RPM (only untill the gears meshed - then up to 2500 – 3400 sound very high) so that the boat wasn't trying to shake it's self appart, the vibration is scarry enough for me to think that it is the lesser of two potential evils. | ||
| Eric Yaremko Unregistered guest Rating: N/A |
Brayden, Went through this 2 years ago re-prop change,did nothing. Sought pro help last year. Problem was getting worse and probably will. The teeth or shaft was "off round" about 1/1000 in. It was milled, rebuilt and the problem went away, cleaning mine alone wouldn't have helped. Good luck on self repair and report back. Couple guys on our site are very skilled machinists/glass guys but I don't think I could pull off some of the repairs listed here myself without making a mess. Also why you running at 1500rpm? I'm no expert but I've been told that running a diesel at essentially 1/2 cruising is terrible for it. The 2GM. lists 1hr max. at 3600, extended cruise at 3400. Diesel guy in our area recommends cruising 3000 to 3200 and if just "kicking" to and from racing to "firewall" it both ways. | ||
| Brayden Woods New member Username: Brayden Post Number: 3 Registered: 05-2003 Rating: N/A |
It's race night tonight, so I will start the debate with my crew over what is the best course of action. The Martec (alternitive) prop that has been "dug up" is a RH 16 inch 12 pitch - So I am not sure that that would make a very good alternative either... chances are we will just take our time motoring, and not be in any hurry (@ 1500 RPM - you can't hurry). Thanks for the advice... | ||
| Scott Corder New member Username: Pastcommodore Post Number: 39 Registered: 02-2001 Rating: |
Brayden, I can't offer any specific advice but I do know that one of the marine yards here in Michigan is VERY knowledgable regarding Yanmar. They ship Yanmar parts all over the globe. You can try calling Brian at Toressen Marine in Muskegon Michigan at 231-759-8596. tell him I told you to call. | ||
| Brayden Woods New member Username: Brayden Post Number: 2 Registered: 05-2003 Rating: N/A |
I have the same chattering prop/clutch problem, and was not concerned about it (since I don't put the boat over 1500 RPM often) until I realised that I will need to be at nearly full power while navigating the niagra river (fairly strong flow). I am considering changing the Prop by yanking the boat ASAP as I need to go and race this coming weekend. I am lucky enough to have a replacement prop that was kicking arround, but have yet to check the numbers for size and pitch. BUT if I go thru this emergancy change and nothing get better, then I will be very disapointed/troubled. I am willing to get into the boat on thursday and (since I have a good anode) am considering trying to clean the "cones". So here are the questions: 1. Where can I get information on how to do this? 2. What kind of tools will I need? 3? What type of solvent will I need? Any and ALL advice is appreciated. | ||
| George Darrell New member Username: George_darrell Post Number: 4 Registered: 05-2002 Rating: N/A |
This is a follow up to my earlier queries regarding what I thought was prop "clatter". I received several useful suggestions and discovered that the problem was the clutch. The clutch was, to use an automotive expression, chattering for several minutes before it would seat and resume normal operation. I have access to a machine shop with pullers, presses and metric wrenches so decided to pull the transmission/clutch and see what was going on. I also have a Yanmar shop manual which is a must. After inspecting the disassembled clutch cone, gears, shafts, bearings etc. everything seemed to be OK. In mikeing the fit of the clutch into foreward gear I noticed that there was excessive variation in depth as I worked around the fit. It was marginally within spec but very suspicious! I decided to reverse the foreward and reverse gears and clutch since they are identical and the problem disappeared. It has been running great ever since! As an aside, a new 12 pitch prop has boosted speed about 10% but Loren Thompson has bettered me with a 14 pitch prop for even greater speed. These Yanmar engines like to work but the clutch may eventually show some strain. | ||
| Scott Corder New member Username: Pastcommodore Post Number: 33 Registered: 02-2001 Rating: N/A |
George, (please forgive the length of my note) I read your last note re Yanmar conical clutches and props and agree with everything you've written, but have a question: You indicated that you changed prop pitch when changing props (gaining an extra knot under power). If you read a post I made much earlier in this same thread on the bulletin board, I mentioned some very strict advice I received from Martec concerning matching prop pitch to the gearbox on the engine. To reiterate: Martec was adamant that the prop be properly matched to each specific Yanmar gearbox to generate maximum thrust at approx 2900 rpm. Anything different and they said bad things could (would) happen (clutch burn out, engine damage, etc.) They also indicated that Yanmar shipped 2GMs with several different gearboxes on a totally unpredictable basis (just whatever gearbox they happened to have on the shelf as they made each engine). This, they said, obviously prevented them from providing any kind of widely applicable formula for prop size and pitch on a Yanmar 2GM. I have a HUGE (and subsequently heavy) hub on my prop (compared to most every other prop I've seen on a 9.1) and clearly have a different pitch on mine (hull 2) versus (for example) Greg Young's (hull 85). Years ago, when inquiring about these clutch and boat speed under power issues, I asked Martec about changing to a smaller hubbed prop that would generate more boat speed and they gave me the answer I just reiterated above. How did you manage to up-size without creating potential problems? I'm not totally unhappy with my speed under power, but hey an extra half knot makes a pretty huge difference when crossing 60-100 miles of Lake Michigan under power on a delivery! I've also posted or read related messages regarding the varying amounts of horsepower generated by different 2GM engines depending on their date of manufacture that may also play into the selection of appropriate prop pitch and resulting boat speed under power? Back to the example of comparing boat speed under power against Greg's hull 85 on all those cross-lake deliveries we've done together over the years: He just plain seems to have about a half to two-thirds of a knot more oomph under diesel than me. (and I know it isn't my bottom, which Gary's keel measuring report clearly confirms). Again, sorry about the long message here... I'm just VERY curious if I should be looking into swapping my prop for a lighter one (faster under sail) with a slightly different pitch that will make my little yacht also go faster under power? I reluctantly must admit that my sudden interest in speed under power is because these days I seem to spend much of my time on the boat with my 3 yr old twins who appear to love being on the boat but only for a couple of hours at a time. I'm very afraid they will melt-down if mom and dad actually try to accomplish a short weekend trip where it takes just a little too long to get there! Can you help a poor father out? p.s. Have a good time this weekend at the NOODS, we'll be thinking of you all and miss being there at the line with Scooter. | ||
| George Darrell New member Username: George_darrell Post Number: 2 Registered: 05-2002 Rating: N/A |
This addresses Jeff Roy's problem (vibration) and responds to the several very informed and useful postings by other class owners. The transmission/clutch assy is usually at the bottom of many drive line problems but I have done several other maintenance chores to tweak the system. I had my conical clutch replaced about five years ago thus felt it was not at the root of my current problem. As of this moment my cutlass bearing is nearly new, my prop is new (a 14/12 pitch which gave me almost another knot), my shaft is aligned all of which is great after the (probably) clutch quits chattering. I think Don Rychlinski has the best approach for starters (clean the cones). If anyone wants advice on a do-it-yourself shaft alignment drop me an e-mail. | ||
| Jeff Roy New member Username: Jeffr Post Number: 58 Registered: 03-2001 Rating: N/A |
Can any of you expand on the clutch issue. My drivetrain has lots of vibration in it. I already replaced the cutlas bearing and cleaned and polished the prop. I am plannig to loosen up the mounts and re-align the engine sometime soon. Where is the clutch, inside the transmission? What is involved in inspecting it? Thanks for any advice. p.s. If I had any more money left I would replace that Martec with a geared folding prop......someday  | ||
| Don Rychlinski New member Username: Kato Post Number: 12 Registered: 01-2001 Rating: N/A |
I had the same problem a few years ago. It felt like one blade wouldn't open. Took the conical parts of the clutch out and soaked them in a cleaning solution. It took the varnish off and I haven't had any trouble since then. | ||
| John Stefancik New member Username: Jstef Post Number: 17 Registered: 01-2001 Rating: N/A |
George/Everyone, I wrong in saying this is the exact nature of folding propellers? If you change speeds or when you first begin moving in gear the blades are not fully opened and tend to vibrate very strongly? My prop has done exactly what you mentioned since I've owned the boat (7 years). We remedy it by changing speeds very quickly (slow-to-fast). If I really need to stop vibration and maintain forward motion, I throw it into reverse then back into forward again. I don't do it alot since it probably isn't good for the transmission, but it stops the vibration every time. John Stefancik Annapolis | ||
| Scott Corder New member Username: Pastcommodore Post Number: 32 Registered: 02-2001 Rating: N/A |
George, I had similar but slightly different problems several years ago. Advice from Martec led to me replacing the clutch. Chances are its conical (cone shaped) and this can cause the problems you're having. I'd check the clutch. If your zinc is mounted in a favorable position, you can slide the shaft back and actually replace the clutch while the boat remains in the water. | ||
| George Darrell New member Username: George_darrell Post Number: 1 Registered: 05-2002 Rating: N/A |
My prop emits a clatter and vibration as engine rpm is increased past 1500 approximately. This prop is a new one but the old worn one did the same thing. After several minutes of running the noise and shaking stops and all run very smoothly. If the throttle is reduced and then sped up it begins again. This all began last season after replacing the Cutlass bearing. Martec has suggested clutch, engine mounts, shaft concentricity and skeg. Anyone else got any theory? | ||
| Deborah Davenport (Ddavenport) Rating: N/A |
Thanks to Paul for the diagnosis on power loss. We just had the exhaust elbow replaced, en route to the yard for the winter layup. What a difference! Our Yanmar maven says that the internal corrosion in the exhaust elbow is a chronic salt water problem - heat plus salt water plus aluminum creates alumigunk. | ||
| Paul Alexy (Palexy) Rating: N/A |
Hey I just picked up 50% more power with my 2gm20 18hp yanmar in Impaulsive #127. The exhaust coupling elbow had rusted more than 50% closed. It needed to be replace and cost 129.00 for the part. I also pulled out the heat exchanger and cleaned it with acid. I replaced the anto freeze with red perminate not green which can corrode the aluminum in the motor. PS I get 2.3 hours per gal now at 6 nk Paul | ||
| Loren Thompson Rating: N/A |
Just as an update. I sent my original 10/14 prop into Martec in Jan. of 2001. They rebuilt the hub and put on new 14/14 blades. They gave me a $50 trade-in for the old blades. I have hull 55 with the 13 HP engine and the standard gearbox. My 'engine power' speed is now .25 to .5 faster then with the 10/14 blades. | ||
| Scott Corder (Pastcommodore) Rating: N/A |
Forgot one thing in my post below: As detailed elsewhere on the board, the Yanmar 2GM varied in horsepower during the years the 9.1 was built. Without checking, I believe HP ranged from 13-18hp. Furthermore, a few boats may have been delivered with 3GM's. Be sure to indicate to Martec which Yanmar you have and verify the HP. I'm sure these factors may affect their advice. | ||
| Scott Corder (Pastcommodore) Rating: N/A |
I want to say that I have posted regarding this issue elsewhere on the board but will elaborate here anyway. Basically, KATO's advice (although very simply stated below) is recommended VERY highly. The proper "match" of prop size and pitch to the engine depends ALOT on the Yanmar gearbox. I have what appears to be a very large (heavy looking hub) martec while most others I have seen look quite light and smaller in the hub. When I called Martec, they indicated that the gearbox (gear ratios) determine what size and pitch of prop should be used. They said the gearbox or clutch could easily be burned out by an improper match. Here's the troublesome part: There were several gearboxes delivered on the 2GM and there is no rhyme or reason as to why and when... as far as I have been able to learn, they just used whatever gearboxes they had on the shelf as they were building them. Thus, there is NO on-size-fits-all answer to this question. Lance's comments on proper operating RPM are also well-founded. The folks at Martec indicated that maximum propulsion (boat speed) should occur somewhere around 2900 rpm for the 2GM. Again, Martec was able to explain this in great detail over the phone. Best bet? Call Martec with the info KATO suggested. They'll advise accordingly and can be very trusted in my experience. | ||
| Loren Thompson Rating: N/A |
Okay, I am back. Is a 14/14 prop working out okay with 9.1s with the smaller 2gm engine? | ||
| L Thompson Rating: N/A |
I need to replace my prop. What is the pitch on 9.1 props? | ||
| KATO Rating: N/A |
call Martec, give them the numbers off the transmission and they will tell you the proper pitch | ||
| Lance Rating: N/A |
I just hit a log and had to replace my Martec. It was a 14" RH (right Hand) with a pitch of 10. It is stamped on the prop but might be hard to read without sanding off some growth. I was doing an ocean delivery and wanted a replacement fast so I got a new one from Martec (about $600) . But the only one they had in stock was a 15" model same pitch. The guy at Martec seemed to think this was fine as "most of these vintage boats were under propped and you can run the Yanmar at slightly lower rpm's and still put the good load on the engine" as diesels supposedly need. I think it worked fine and I'm sure I've picked up a little speed too! | ||
| Paul Alexy (Palexy) Rating: N/A |
Haztobefast sold to Paul Alexy Now Impaulsive in Melbourne Fl....need help with folding prop size and pitch for 2gm 18 hp Yanmar... |
