So I just picked up a new to me 2003 Grady 180 with 115 Yamaha 4 stroke. Love the boat so far but have been able to take it out 3 times so far and have noticed it has a nasty tendency to continuously porpoise. So my question is has anyone done an aftermarket trim tabs install and what kind of prop are you running? Thanks in advance.
Grady 180 sportsman help
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I have the same boat. 2004 with 115 Yamaha 4 stroke. No trim tabs and never noticed this. Are you trimmed down to where you need to be to take off and ride on plane? Maybe a prop issue? Weight in the boat? Don't be afraid to make someone sit up front. This is an 18' boat with a steep keel so the captain must keep the crew where the ride is best.
Just sort of repeating what Angler was saying... Most boats will porpoise if they are trimmed too high - with variables being speed, sea conditions, weight in the boat and where the weight is placed, among others.
Is this your first boat?
Is this your first boat?
Like Dennis says, the motor may be trimmed up too high.
I apologize if you already know the following but just in case, here are some hints
Trim it down all the way. If trimming is new to you, that means use the tilt and trim switch until the motor is as close to the transom as possible. At minimum trim angle, the motor should be angled toward the hull a bit not just parallel to the transom.
Go for a ride with minimum trim and see if the boat porpoises. It shouldn't. If it does something is rigged incorrectly. If it doesn't, at cruise speed slowly trim up. Do that by tapping the up trim button in short bursts, say one or two seconds at a time. After each adjustment give the boat 10 seconds or so to adjust. Repeat the steps until the bow starts to porpoise. Then trim the motor down a tick or two. That puts you in a decent position.
There is no optimal trim angle for a motor/hull combination. It changes with speed and sea conditions. Over time, you will get the feel of trim adjustments.
FYI, if you trim up too far, the motor will start to ventilate. That's when the prob is coming out of the water stream. Ventilation is to be avoided; in addition to possible loos of control, you can starve the motor for cooling water or over rev.
I apologize if you already know the following but just in case, here are some hints
Trim it down all the way. If trimming is new to you, that means use the tilt and trim switch until the motor is as close to the transom as possible. At minimum trim angle, the motor should be angled toward the hull a bit not just parallel to the transom.
Go for a ride with minimum trim and see if the boat porpoises. It shouldn't. If it does something is rigged incorrectly. If it doesn't, at cruise speed slowly trim up. Do that by tapping the up trim button in short bursts, say one or two seconds at a time. After each adjustment give the boat 10 seconds or so to adjust. Repeat the steps until the bow starts to porpoise. Then trim the motor down a tick or two. That puts you in a decent position.
There is no optimal trim angle for a motor/hull combination. It changes with speed and sea conditions. Over time, you will get the feel of trim adjustments.
FYI, if you trim up too far, the motor will start to ventilate. That's when the prob is coming out of the water stream. Ventilation is to be avoided; in addition to possible loos of control, you can starve the motor for cooling water or over rev.
I should have added a bit more info. No this is not my first boat and I’m aware how to trim it out correctly. Weight definitely could be a factor though as I am new to this boat so just getting use to it at this point. Even in flat calm conditions the boat still wants to porpoise and gets into an annoying rhythm where I either need to adjust power or trim down to stop it. Even with 2 guys on the boat it seems to take a bit to get on plane. I checked the prop yesterday and it is a aluminum prop 17 pitch. Being in the northeast (New York harbor area) the wave length and chop is never the same or any pattern to it almost what so ever.
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Grady's are heavy, even your 180 compared to other brand boats your size. Problem may be in your prop. Aluminum will flex on takeoff compared to stainless causing the long time for planning out because the blades are flexing and loosing bite. Being aluminum, previous owner might have dinged prop causing it to loose bite, loss of cup in prop. Might try borrowing a stainless in 17P and see if that helps with your issues. Over trimming and/or loss of cup/bite in prop will cause porpoising. I'm spinning a 4 blade stainless on my F225 and am very happy with the performance.
You might try using a hydrofoil on the engine. In my experience this has always improved planing time and minimum planing speed. I can't speak to the porpoising but I would imagine that it will help control that issue as well. They are around $60 online.
As far as the hole shot goes, that's hard to address in terms of whether what you are experiencing is normal for that boat/engine combo or if your expectations are too high. It's really hard to quantify this via a forum when we only have "opinions" to base this on. However, if you can get the engine well into it's operating range (ideally upper end) for MAX WOT, then you're at least doing OK, there. This would be done, normally, with a light load. When you bought the boat, did you have a survey done... which would often include a compression test... what are those numbers? If not, do one and post the numbers.
Some boats don't like as much UP trim as others... so this is another case of maybe you're comparing what you're used to to this new boat. The amount of trim vs weight placement in the boat vs speed is another thing that can easily change from boat to boat. But trimming down when the hull starts to porpoise is a normal thing to do - and an expected thing to do. Also, a little boat is more susceptible to weight distribution than a larger boat. From what you've posted, it seems like what you are experiencing is perfectly normal. Keep in mind that we can only go off of what you are writing, so if there's more too it then more info or a video is needed.
I would refrain from doing any alterations until you first find out if the engine is healthy, mounted correctly, and the prop is properly sized and in perfect shape. To do other wise would be simply putting a bandaid on a problem.
What sort of boats have you owned before?
Some boats don't like as much UP trim as others... so this is another case of maybe you're comparing what you're used to to this new boat. The amount of trim vs weight placement in the boat vs speed is another thing that can easily change from boat to boat. But trimming down when the hull starts to porpoise is a normal thing to do - and an expected thing to do. Also, a little boat is more susceptible to weight distribution than a larger boat. From what you've posted, it seems like what you are experiencing is perfectly normal. Keep in mind that we can only go off of what you are writing, so if there's more too it then more info or a video is needed.
I would refrain from doing any alterations until you first find out if the engine is healthy, mounted correctly, and the prop is properly sized and in perfect shape. To do other wise would be simply putting a bandaid on a problem.
What sort of boats have you owned before?
On a previous boat that I owned, I had porpoising problems. A guy that owned the same boat and had worked at rigging boats at a large marina/dealer for years before retirement ask me what bracket hole the engine was mounted at. The guy I had bought it from had raised the engine as high as it would go, the last hole, in search of that mythical magical extra mph that doesn't exist. I related this to the old guy that was advising me and without hesitation he said to lower the engine to the next to lowest position. I hated to go through all that when it didn't seem like that could cause my problems. I did wind up lowering it to the position he recommended and it was like a different boat. The porpoising could be turned on by trimming up and as I trimmed down it would lessen until ceasing all together at some point, depending on my loading. I wish the guy didn't live up in the North East cause I owe that man a steak dinner. Long story here but have a look at your engine height and give some pondering time to all the recommendations the guys on this forum are offering. Lots of years of accumulated experience here.
Are you sure it is aluminum? Put a magnet to it. Likely painted stainless. Mine is an OEM Yamaha 13x17 K and it is black painted stainless but sure does look like aluminum and what I first thought. GW does not cheap out when putting these together, I promise you that. Could be aluminum though and would change that out to a stainless if I were you. Aluminum will flex and this little boat weighs more than some 20'ers.
What you are describing certainly sounds weird. I have had my boat out in some of the nastiest weather with 6-7' rollers (not on purpose). Was not fun and was crawling but getting on plane without trim tabs or any major porpoising.
If it were my boat, I would review how much weight you have and where it is located. I already mentioned crew but there are some other heavy items to consider. There is a 60 gallon fuel cell in the floor under the console. I rarely fill mine and usually keep 20-30 gallons in there. I keep my 19 gallon water tank in the console about 1/2 full and never fill it either. One 24 series battery in the rear port side compartment and a 27 series on the starboard side. There is an extra 10 pound anchor back there somewhere too. Beyond this, I travel as light as I can only inviting slender super models with no gear on my boat. :lol: OK, so I did say invite but does not mean they ever join me.
Usually a 1-2 guys with some gear. Still, even with 3 in the boat it is fine. Wished I had a 150 when 1 of the heavier friends show up but might be cheaper just not to invite him anymore than to upgrade my outboard.
Another thought could also be a bent prop or prop shaft? Or maybe a spun hub? If it is not spinning in perfect revolution I guess it is possible to attain enough trim to plane out but enough to give you what you are seeing?
Is you motor trimming all the water down? Have you checked your fluid level? If it is lacking fluid, it can affect it's range.
Last thought and really hope this is not the case for you but could you have a wet transom? You would notice this though when the boat is not moving and the scuppers would be taking on water or splashing a lot. That is a thick transom but also means that the plywood can soak up a lot of water. Usually rain water but never the less.
Anyways, good luck and keep us posted. Hope you can figure it out. If you need any pictures or measurements for compassion, please let me know as I would be happy to help out.
What you are describing certainly sounds weird. I have had my boat out in some of the nastiest weather with 6-7' rollers (not on purpose). Was not fun and was crawling but getting on plane without trim tabs or any major porpoising.
If it were my boat, I would review how much weight you have and where it is located. I already mentioned crew but there are some other heavy items to consider. There is a 60 gallon fuel cell in the floor under the console. I rarely fill mine and usually keep 20-30 gallons in there. I keep my 19 gallon water tank in the console about 1/2 full and never fill it either. One 24 series battery in the rear port side compartment and a 27 series on the starboard side. There is an extra 10 pound anchor back there somewhere too. Beyond this, I travel as light as I can only inviting slender super models with no gear on my boat. :lol: OK, so I did say invite but does not mean they ever join me.
Usually a 1-2 guys with some gear. Still, even with 3 in the boat it is fine. Wished I had a 150 when 1 of the heavier friends show up but might be cheaper just not to invite him anymore than to upgrade my outboard. Another thought could also be a bent prop or prop shaft? Or maybe a spun hub? If it is not spinning in perfect revolution I guess it is possible to attain enough trim to plane out but enough to give you what you are seeing?
Is you motor trimming all the water down? Have you checked your fluid level? If it is lacking fluid, it can affect it's range.
Last thought and really hope this is not the case for you but could you have a wet transom? You would notice this though when the boat is not moving and the scuppers would be taking on water or splashing a lot. That is a thick transom but also means that the plywood can soak up a lot of water. Usually rain water but never the less.
Anyways, good luck and keep us posted. Hope you can figure it out. If you need any pictures or measurements for compassion, please let me know as I would be happy to help out.
Thank you all for the responses so far. I’m going to take a look into all of these things further. I think a lot of it has to do with the weight of the boat and the overall weight distribution. I’m going to take some notes down next time on the water and play around with rpms, trim position, and weight distribution to try to get a better grasp on what is exactly going on. I’ll let you guys know how it goes.
NHAngler wrote......."Beyond this, I travel as light as I can only inviting slender super models with no gear on my boat. OK, so I did say invite but does not mean they ever join me. Usually a 1-2 guys with some gear. Still, even with 3 in the boat it is fine. Wished I had a 150 when 1 of the heavier friends show up but might be cheaper just not to invite him anymore than to upgrade my outboard"......
I dealt with the same dilemma as far as weight goes. We anchor a lot in the gulf while snapper fishing and I found that anchoring is such a complicated specialized operation that I needed a bigger crew to deal with the anchoring process. I also figured out that having several of the big lumbering, beer guzzling hulks that I normally take was not in the cards weight wise. Therefore we settled on a more light weight anchor crew. They were quite inexperienced at the anchoring process so we have, out of necessity, had to resort to multiple practice drills each day to make sure they stay sharp and ready for any eventuality. This same theory could help deal with porpoising as the crew can be moved about the boat to properly distribute weight.
I dealt with the same dilemma as far as weight goes. We anchor a lot in the gulf while snapper fishing and I found that anchoring is such a complicated specialized operation that I needed a bigger crew to deal with the anchoring process. I also figured out that having several of the big lumbering, beer guzzling hulks that I normally take was not in the cards weight wise. Therefore we settled on a more light weight anchor crew. They were quite inexperienced at the anchoring process so we have, out of necessity, had to resort to multiple practice drills each day to make sure they stay sharp and ready for any eventuality. This same theory could help deal with porpoising as the crew can be moved about the boat to properly distribute weight.
Halfhitch, I'm just considering screw....oops crewing on your yacht. What would the cost be for an afternoon? I am good on the anchor!! Make that in Canadian dollars. Looking forward to a positive responce! Cheers trapper
On your 180, do you notice a list or heavier side while riding? My port side sits a bit heavier in the water...
I have a 2001 with a 130 2 stroke, the only time I get some porpoising is when I have to many people in the stern...just shift the weight! Small boats tend to have smaller "issues" get magnified!
I have a 2001 with a 130 2 stroke, the only time I get some porpoising is when I have to many people in the stern...just shift the weight! Small boats tend to have smaller "issues" get magnified!
Halfhitch, I believe I have offended you with my attempt to join your beautiful crew (figureheads or bottoms) onboard your yacht. For this I apologize. I 'm sure you can manage all as shown by yourself. Yes it was a weak moment on my part. Because we do not see much of that up here on Vancouver Island I momentarily lost my sense of decency. With appreciation, trapper :mrgreen: p.s. I do not believe your yacht will ever porpoise!!!
trapper said:
Hahaha...Not offended at all trapper. Actually I haven't been on the site for awhile. I have been busy building a shed and outdoor kitchen area before it gets hot down here. As far as helping the anchor crew goes, actually a buddy sent me that picture and I just get a kick out of working them into a story. We both know that the cost of owning a boat is great enough without dealing with the maintenance issues of such a crew.
This the shed that has kept my attention...
Halfhitch, I would not consider that a shed, more like a small backyard res. and very nicely done. Can totally relate to building. Built a 800 square ft shop wired and plumbed years ago which we lived in while I built the 2000 sq. ft. house. Last project was a 750 sq. ft boat house which I had to remodel a little to fit the Grady. Anyway nice work and a beauty place to hang out on those hot Florida days when you cannot join the babes on the yacht. Cheers, trapper :goodjob