Cutwater - Trim Tabs too small

This is just a pet peeve in what is a serious and useful discussion. But do you knowledgeable boaters seriously think that a boat riding above its bow-wave is called "planning"? That's what you do when your daughter's wedding is coming up.
Cheers, Roger, C28, Kingston, ON
 
aintmissb - this is a boating forum. No need to point out typos, spelling and grammar errors unless the meaning or the post is unclear. (And, yes - I did notice that this message has a typo, but I decided to leave it in.)
 
While I am not an expert on trim tabs I would say that some of the complaints, and therefore suggested fixes, come from some individual expectations or desired results outside those of Ranger Tug. In many cases making the boat something it was never intended to be. My first assumption would be that Ranger Tug folks have carefully designed, chosen and tested equipment for each boat model. I am sure they work with the manufacturer on specifications for operation, safety and liability. I am sure this was a consideration when they put a 300 hp motor on a boat that used to have a maximum speed of about 14 mph. I have had my R27 top out at 38 mph. Changes everything.
Specifically with regard to the trim tabs. Mine do everything I need them to do. When it was delivered I was warned not to make a trim tab adjustment when going fast. I forgot that once and almost did a 45% degree turn in a hurry. Never again. I would hate to see what could happen with larger tabs. Looking at my current tabs I am not sure there is room for larger tabs.
You see these discussions about props all the time. Then I read an article that said - because the manufacturer wants the engine to perform optimally you can bet they put the best prop on for the desired operation. to do otherwise would be shooting themselves in the foot. Makes a lot of sense. Having said that there are folks out there that want a different result. That is why they make so many different props and manufactures are more than happy to sell you one.
Since I was not involved in the development of the boat, sea trials and subsequent adjustments I will leave that to Ranger Tug crew. As long as they delivered what I paid for I cannot expect them to adjust to my individaul desires. If I want to make a change that is up to me. But I do that without all their expertise on why it was the way it was. The trim tab manufacturer may have a differnt opinion but he is not the boat manufacturer. So as long as RT did not exceed their recommenation, which would be a saftey issue, I am satisfied with their decision.
 
Matty":3lxtanau said:
While I am not an expert on trim tabs I would say that some of the complaints, and therefore suggested fixes, come from some individual expectations or desired results outside those of Ranger Tug. In many cases making the boat something it was never intended to be. My first assumption would be that Ranger Tug folks have carefully designed, chosen and tested equipment for each boat model. I am sure they work with the manufacturer on specifications for operation, safety and liability. I am sure this was a consideration when they put a 300 hp motor on a boat that used to have a maximum speed of about 14 mph. I have had my R27 top out at 38 mph. Changes everything.
Specifically with regard to the trim tabs. Mine do everything I need them to do. When it was delivered I was warned not to make a trim tab adjustment when going fast. I forgot that once and almost did a 45% degree turn in a hurry. Never again. I would hate to see what could happen with larger tabs. Looking at my current tabs I am not sure there is room for larger tabs.
You see these discussions about props all the time. Then I read an article that said - because the manufacturer wants the engine to perform optimally you can bet they put the best prop on for the desired operation. to do otherwise would be shooting themselves in the foot. Makes a lot of sense. Having said that there are folks out there that want a different result. That is why they make so many different props and manufactures are more than happy to sell you one.
Since I was not involved in the development of the boat, sea trials and subsequent adjustments I will leave that to Ranger Tug crew. As long as they delivered what I paid for I cannot expect them to adjust to my individaul desires. If I want to make a change that is up to me. But I do that without all their expertise on why it was the way it was. The trim tab manufacturer may have a differnt opinion but he is not the boat manufacturer. So as long as RT did not exceed their recommenation, which would be a saftey issue, I am satisfied with their decision.
Click to expand...

I respect all of your opinion and agree with most of your post in regard to Ranger Tugs. Ranger Tugs have a different designed hull then the 26, 28, and 30 inboard Cutwater. I can't speak for the performance or running attitude of your Tug and how it reacts to trim Tabs being deployed at a higher RPM. First the 27 OB is not in the same conversation. It is a planing hull. Honestly a planing hull should have little or no tabs deployed when on the top of the water( above 30 mph) I can say there is a noticeable difference in the hulls. Cutwaters are step hulls. Step hulls are normally used in high performance hulls. The Cutwater being a semi-displacement is not a high performance boat but is designed to utilize the same benefits of the high performance Hull. The step at the forward section of the hull helps to distribute air across the aft section of the hull reducing drag and increasing performance. This works quite well with a( light boat ) and the factory installed trim tabs. My 26 Cutwater when empty, My wife and I (Full Tabs) at high cruise speed performed as designed. Now add the fact that the tabs are not installed as the manufacturer recommends and this was acknowledged by Cutwater that they are mounted "slightly higher then normal" reason for (Full Tabs at near or WOT). Still the boat operated light boat as designed. Now add equipment, Fuel, water, a Rib with out-board and four people sitting and relaxing in the cockpit and take them for a ride to the next harbor down Lake Michigan 20 miles for lunch. Kick up the throttle and cruise at 15KT full tabs and struggling to see out of the windshield because the bow is so high. The selling point of the Cutwater was Semi Displacement with performance. The other issue is the boat digging so deep really loads the engine. Normal WOT is 4140 rpm. Rpm with passengers and gear 3800 ( below manufactures specifications for engine load). So at cruising speed 3600, GPH is 9.5 (light boat) but with the boat digging heavy load 10.5 GPH. GPH are associated with engine load. Now add some additional trim tab size or alterations and what is the result. Same boat, same Load( passengers and gear), Full tabs, Bow down, Cruising speed 3600, GPH 9.8,WOT RPM 4010 all maintaining the Volvo design operating conditions. Now Lighten the load and take the boat out, Bring the boat up to high cruising speed if full tabs are used the bow comes down as slowly bringing tabs down to a comfortable trim to achieve proper attitude. And yes if full tabs are used the bow will dig and the boat will not handle properly. This is called adjusting the trim tabs based on load. The goal was to have the boat perform properly with all loads and conditions.This is an area (my opinion) that fluid motion (Cutwater) fell short at.I do maintain a Log and log every trip that includes passengers, fuel, cruising speed, sea conditions, temperature. I see a definite advantage to installing larger Tabs or in my case Alterations.I actually know through messaging that many 26 and 28 Cutwater owners have the same opinion. The boat handles quite well with (18x12) tabs that was recommended by Bennett instead of the 12x12 installed by Cutwater. It is a tight installation but it will work and adds to a loaded Cutwaters performance. I will say you must know how to trim a boat properly based on conditions. I would think that most Ranger and Cutwater owners are experienced boaters so this should not be an issue. If you are satisfied with your Ranger or Cutwaters performance and feel that it is adequately equipped with proper trim tabs this post is not a subject that you are concerned about and would have a different opinion and honestly that is good. That is what this forum is all about opinions and experiences.
 
Thanks for all the info BB marine.
When it has new bottom paint, my C28 (with generator) can reach speeds of 20 kn. However when kept in the water, that "clean" condition only lasts weeks in the warm waters here in SC. Marine growth and loading drops top speed to about 15 kn max, or normal cruise of 10-12 kn, even after routine bottom cleaning by diver. I could definitely benefit from more trim-tab control at these low speeds. I am moving the boat to a dry stack which should help reduce marine growth, and have ordered the trim tab drop fins you suggested ($30 - cheep for a boat addition). Your detailed discussion of this topic has been a great help.
 
Lots of good info Brian..i may become an expert yet if i keep reading.
Thanks
 
Maybe there is something wrong with Dona Sea.

I have had no such issues with my 2018 CW28. Although still learning the boat, I have very little port list at rest, and don't bother with tabs below planing speed. Once cruising over 2500 RPM, the trim is helpful to get the bow down (to a point). But at higher cruise speeds, if anything my trim is VERY effective. I have to be careful not to apply too much trim on one side or the boat will quickly roll significantly, so a couple of short 1 sec blips of the appropriate tab is plenty to get it level unless everyone is on one side of the boat.

That 8.5' beam is pretty narrow given the hull length, and the list I experience is about what I expected - they do like to roll with shifting weight compared to the wider beams. How does it act when your 5 or more people get on one side at the dock? Mine will list quite a bit...

mike
 
Tardis - what year is your boat, and engine do you have? Wondering if something else is going on there. I get 27kts WOT at 3500R. Boat is 2018 with 260 HP. A nice cruise setting is about 2900 R, 18Kts, and 8 gph. That's with a genset, no dingy, and 2 folks up front with 3/4 or so of fuel. Mr. Volvo says that 14 PSI boost is a sweet spot for this engine. On it's first (clean) coat of bottom paint, but in fresh water now.

mike
 
I believe the tabs on our R31CB were too small.
Rather than replace, I added Bennett Fins to increase the lift.
Seems to improve both speed and efficiency.
Still working on overheating over 3000 RPM as 3150 is 2 miles faster with same fuel economy.
Replaced thermostat, no chance to test yet.
Bill
 
mferguson":37h4ec8v said:
Tardis - what year is your boat, and engine do you have? Wondering if something else is going on there. I get 27kts WOT at 3500R. Boat is 2018 with 260 HP. A nice cruise setting is about 2900 R, 18Kts, and 8 gph. That's with a genset, no dingy, and 2 folks up front with 3/4 or so of fuel. Mr. Volvo says that 14 PSI boost is a sweet spot for this engine. On it's first (clean) coat of bottom paint, but in fresh water now.

mike
Click to expand...

I agree with you that Tardis numbers are low in comparison to other 28 Cutwaters owners that I have talked to. Your numbers are very good, I haven't known any Cutwater 28 owners averaging 31mph WOT . That is great! The Cutwaters, 26 more, but also the 28 react significantly different based on load. 2 passenger sitting forward with 60 gallons of fuel, clean bottom is a light load, and should be close to manufacture specs and in your case is, if not better. For most of us these specs are hard to meet with boats loaded for cruising the way many have intended to use them. An example: I will use a Cutwater owner that finished the loop. He was a solo Looper. He was known by Loopers as "Speedy" He cruised at 22 kts (25mph) but his average speed was 18kts (20.5 MPH). He had no trim issues, good performance, burning an average of 10.8 gph averaging 1.93 mpg. Clean bottom. I met up with him this fall when cruising the Tennessee river, we had a few docktails and commiserated about our Cutwater boats. His biggest complaint was, it performs great with me aboard but if I have my family onboard its a completely different boat, "I can't trim it", "the bow won't come down at all", "if two people are sitting on one side I can't get it to level I have no more trim range", "My performance drops considerably" I told him we experienced the same issue and possibly worse because of a 2' difference in LWL ( load waterline length ) slightly reducing the efficiency with the same hull design. So in Tardis's case a dirty bottom seems to change performance. Clean bottom 20kt does seem low. The power plant can be operating correctly but if the sea water is warm and air temperature warm, the engine's aftercooler using warmer water and higher ambient air temperatures effects performance, ( especially in Cutwaters having no engine compartment ventilation) Tidal and river currents along with water conditions, boat load and the inability to lift the stern to reduce the big hole and large wake behind the boat can effect performance. The most important issue to always address with these high speed small displacement engines is the engines ability to always hit max RPM in all running conditions. You never want to load the engine down. When I hear an owner of a D4 say "the most I can get out of the engine is 3350 RPM . " I cringe I would rather see 3550rpm for engine longevity. The same with D3's , 4140 to 4000 no lower, is my goal. Along with 11.8 gph at 4000rpm under 100% load 220 hp, with a sweet spot of 3380 rpm 8 gph 20psi boost just under 70% load 13kt (15mph). It is interesting to see the performance differences from one boat to another but if we were comparing apples to apples same load, water temperatures , currents, ambient temperatures and water conditions I think we would find the comparisons closer.
 
Since my post on speed has generated some discussion, let me give some additional details.
I have a 2013 C28 with diesel D4 260 engine. It is loaded - AC and generator, etc. as it was briefly a dealer demo. I usually have 4 adults aboard, plus gear, so I am carrying a bit extra weight.
Engine spec is 3500 WOT. I can hit about 3350 with my prop when all is clean.
BoatTest ran an article on a similar C28 about 5 years ago and found top speed was 27 knots with a light load.
My experience is that I once was able to hit 24 knots, but not for long. In the warm waters here in SC fouling happens quickly. A diver cleans the hull at least every month in summer, but he cannot get everything. As you know, even a small amount of marine growth on the prop or a running surface will cut speed a good bit. My usually cruise is about 12 knots at 2700 rpm. According to the BoatTest performance table I should be doing about 17 knots at that rpm. so I have a lot of drag.
When I pulled the boat out last month I was horrified by all the marine growth (oysters, barnacles, grass) that was on the running surfaces, in both thruster tubes, and even partly into the exhaust (where the rubber covering flap is gone). Currently I am scheduled for bottom paint, and have given up my marina slip. Henceforth I will be keeping the boat in a dry stack, so I expect my performance to improve. Will not know for a while, though, as currently my engine is acting up - dropping back to 1500 rpm (safe mode?) whenever the rpm exceeds that. No error codes though, but that is another issue not worth pursuing until the hull is clean.
 
I have listed a set of Bennett trim tabs complete, backing plate, hinge plate , custom drop fin, and planes (Cutwater for sale) If interested PM me.
 
Over the winter I removed the factory installed Bennett trim tabs so that I could install larger planes. The trim tab original installation was not to Bennett installation specs ( mounted to high). Before installing the new 18x12 planes I filled the original fastener holes with west system epoxy and drilled new hole to move the planes to the proper mounting location 1/4" off the bottom leading edge, 5/8 " trailing edge. I spoke with a Bennett rep about benefits I experienced with the drop fins and asked about changing to the 18X12 so I could rack store the boat while in Florida. I was worried the forks from the truck would damage the drop fins. He felt that the benefit would be equal 12x12 plane with drop fin would = 18x12 without fins. I know of another Cutwater owner that did the same install and has realized the benefit. The 18 x 12 just fit. I'm posting a few pictures of the larger tabs installed.







 
be interested to hear how this tests in the water this year
 
After three sea trials on Lake Michigan the larger 12 X 18 Bennett planes are a large improvement over the original installed 12 X 12 planes. I think they are equivalent to the custom drop fins that I made last year but I now do not have to worry about damaging the drop fins when I rack store the boat. Two week's ago we took a short 29 mile trip in what was forecasted as 1' to 3' with a 4 sec per. seemed closer to 2 to 4's. I'm cruising a bit stern heavy this year, Rib with 9.9 outboard, Aux fuel tank full, main fuel tank full, and additional weight from new Northstar AGM's 18lbs each heavier then original installed Centennial maintenance free. 72lbs more weight just in batteries. I was able to cruise and maintain 12.5 kts 3300 rpm with the bow down and cutting into the waves smoothly. I kicked the throttle up WOT 3980 18kts bow still down with a slight reduction in trim it still handled good with some hull pounding but very comfortable. I backed down to 3450 rpm the boat handled the short chop 1 to 3's nicely at 14kts. On the way back we had a following sea. I gained a bit 3450 rpm averaged 15kts and WOT was 4050 19.5 kts and an impressive smooth ride.( very little spray from the dingy ) I didn't want to back down on the throttle but the little D3 was screaming, so I backed down to 3450 maintaining 15kts. The additional weight added to the aft, 72lbs for batteries , 140 lbs fuel in aux tank full, 30lbs heavier outboard, 20lbs motor davit all added aft weight. I lost 100 rpm and 1.5 kts. I would loose considerably more if I was running standard 12 x 12 trim tab planes. I highly recommend larger planes or drop fins on the C26 if you plan on cruising with equipment on board or additional passengers.
 
I added Bennett fins to my tabs, improved R31CB performance.
 
I have a 2018 Cutwater 24 coupe and I add a 3 inch by 7 inch extension on the port side trim tab and now with people on the port side I can make the boat level with no problem. I had a problem before if I had a couple of people on board, it seems they wound up on the port side and was hard to get the boat level.
Ken
 
The port side list is common with single screw right hand rotation props. Then add a few items and passengers on board and it can really cause a list. The issue I see with your solution is what happens when there is equal weight and or slightly more on the starboard side. Having one tab that has the ability to compensate more than the other could be problematic in some sea conditions. My opinion is what ever alterations you make to one plate you should make to the other. Either install larger plates ,extensions both sides or drop fins both sides. Having one side react differently then the other could cause an issue in running attitude and compromise the boats sea handling characteristics.
 
I haven’t seen any negative affects so far. I just don’t run as much tab on port side if not needed. Boat seems fine at any speed. I didn’t notice a difference at all with just my wife and I.
Ken
 
ken,
you are one very smart person. I don't think I know of any man, that should notice his wife making a difference in the boats handling, and live to tell about it. Unless perhaps she is using him to troll for alligators ...

Stuart
 
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