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Author Topic:   Trim Tabs on 18' Ventura
smausert posted 04-30-2004 08:48 PM ET (US)   Profile for smausert   Send Email to smausert  
I am seriously considering adding trim tabs to my 2001 18' Ventura (yep it has the notch) and the 150 Optimax is in the third hole from the bottom. The motor appears properly aligned with the bottom based on statements from Whaler and the dealer. It does not porpoise but the boat just doesn't plane well and the bow wants to stay up! And if you want to see a sorry hole shot just take a look right here. I have ordered a Turbo lift just to give it a try but was wondering if anyone has added any of the Bennetts or Lenco tabs. I am particularly interested in the M120s or M80s - has anyone tried these on this boat Since I have the stern ladder which we use quite a bit I am looking for tabs that will fit under it meaning a 12 inch chord might be too much though measurements seem to indicate it will just barely work. I have a stainless prop on the motor which matches what mercury and the dealer recommended (checked this last year and don't remember the details). Anyway, if anyone has done this I am very interested. I searched the forum quite a bit but didn't find much. As a new comer to the forum just tell me if this is old news and done. And of course a point to the messages would be good!


JohnJ80 posted 05-01-2004 05:58 PM ET (US)     Profile for JohnJ80  Send Email to JohnJ80     
My experience is that Whaler's (which is no doubt the same as the dealer) engine height recommendations are very, very conservative. As for the dealer, 90% - no, make that 98% of them don't have a clue what happens when you raise the motor, they always put them all the way down and pretend they know what they are doing. It is shocking how little they know about this.

If I understand you correctly, your motor is only up one hole from all the way down. Is that correct?

If so, then I am pretty sure you can go higher and should. Many here seem to find that being 1.5" above the bottom of the hull is better. Whaler recommends 0-3/4" and admits that is conservative. When I went through this with my repower on my Dauntless 15, I wound up putting the motor all the way up after experimenting with every hole from there to all the way down. I was shocked at the difference that made.

Moving up a single hole makes a big - surprisingly big - difference. Grand Island Marine will tell you to move your motor ALL the way up when you install the Turbo Lift. If I had to do this again, I would go all the way up and work my way down. As long as you have cooling water and the prop doesn't blow out, you are better off with it up.

Since you have ordered your Turbo Lift, I would move the motor up first then add the turbo lift and then decide if you need tabs. Do these things one at a time. Although, since you have the T-L that will want the motor all the way up - you might just want to go there first try it and then add the fin and try it. Just make sure you have cooling water peeing out the back when on a plane.

Tabs are really cool and you probably don't need the fin once you have them (although it will help your hole shot some anyhow).

Plan on a morning at the boat launch to move your motor up - you can do it on the trailer with the right tools, no sweat. It is a process of experimentation and you just need to do it.

Here is a link to how to raise the motor:

Here is a link to my repower that sounds like it started pretty much with the problems you have.

Good luck, let us know how it goes.


davej14 posted 05-01-2004 08:05 PM ET (US)     Profile for davej14  Send Email to davej14     
How would I contact Grand Island Marine to discus the turbolift fins. I have a "new to me" Dauntless 14 with a 75 Merc 2-stroke ELPTO and I have a feeling that I may need to contact them. I haven't actually had the boat in the water yet, but after reading the posts on the D15 I am going to check the engine height and do a little experimentation as soon as i can hit the water. If anyone has experience with the D15 with a 75 Merc. i would sure like to hear them.
smausert posted 05-01-2004 09:27 PM ET (US)     Profile for smausert  Send Email to smausert     
The motor is actually two holes from being all the way down. The mounting bracket uses five hole flanges (4 of them) and the bolts that go through the transom are through the middle holes of these flanges.

You are quite right about Tom at Grand Island Marine. With the TurboLift installed, he believes higher is better provided you have the cooling you need. The difference in his and your recommendations are that he (and I) believe it is best for me to start with the motor where it is because I know the characteristics of the boat with the motor in this position quite well and will be able to tell immediately if there is improvement or it is worse. Then as I move the motor up I will be able to really understand the performance change if any. I really do wonder if a single hole change can really make a difference!

I found Tom at Grand Island Marine to be quite interested in this problem and would encourage others having similar problems to get in contact with him as follows:

Phone: 321-452-8126
Address is as follows:

Grand Island Marine
180 South Banana River Drive
Merritt Island, FL 32952

He is also sending a diagram of how to move the motor while the boat is on the trailer. Sounds similar to your referenced procedure. Since my motor is fairly heavy (430lbs) it will be interesting to see if can be done as he described. My boat is hung in a boat house set up with a work platform built to work around the motor and stern of the boat (requires the boat to be backed in) and I may be able to mod the procedures and just do it there. Of course, I will have a block and tackle set up to secure the motor just in case!

On the topic of trim tabs, I found another manufacturer by the name of Trim Master. Just wondering if anyone has experience with these tabs. I took some advice from Bennett today and did a little mock up of an M120 tab. It will not fit under the stern ladder so that is one option I have eliminated. I need a tab on the order of 12 by 10 (span by chord) to fit in the space I have available. Just not sure if that size can cure the problem.

Thanks again for the help.

davej14 posted 05-02-2004 10:50 AM ET (US)     Profile for davej14  Send Email to davej14     
I contacted Tom at Grand Island Marine today. They are designers and not actually a marina as I thought. Even though i caught him at home on Sunday when they are normally closed, Tom was very cordial and is sending me a brochure on his turbolift fins. He said they are stainless and their design allows them to be "clamped" onto the motor, in my case a 75 HP Merc 2-stroke. Price is around $165.00. I couldn't find anything on them outside of this forum so if anyone is interested, I'll scan the brochure and post a link. I'll be away for about two weeks so will do it when i return. Meanwhile, if anyone has a picture of an installation it would be appreciated.
TRAFFICLAWYER posted 05-02-2004 11:22 AM ET (US)     Profile for TRAFFICLAWYER    
You can contact Bennett at

AKA Tabman
or the hull truth

JohnJ80 posted 05-02-2004 12:54 PM ET (US)     Profile for JohnJ80  Send Email to JohnJ80     
You will be able to move your motor with the procedure that Tom provided. It is really easy since you have this very long lever arm that your trailer becomes. It is no problem.

If you have a block and tackle in your boat house and an attachment point that's ok, you won't have problem either.

The Turbo Lift is a great product.

Tom is right, it is easiest to put on the TL first and then test it. However, all that being said, you still want to raise the motor as high as you can get away with it so that you have the minimum drag in the water when underway. Even if this solves your problem, I would be still messing with raising the motor.

One hole can make an enormous difference. When I repowered by Dauntless, the dealer mounted the motor all the way down, mistakenly believing this would help my rather mild porpoising problem at the time. When put the boat in the water, the hole shot stunk (I couldn't see over the bow of the boat), it took forever to get on a plane, then when I hit any waves - anything over flat water - the shock was so bad that I thought I was going to knock my fillings loose. The only speeds I could run the boat without wierd handling characteristics were idle and WOT.

Moving up one hole made it a whole new boat. When I got it up all the way it was absolutely unreal how sweet the boat now rode and how well it handled. I then added a TL for hugely increased hole shot and improved trim range.

The single biggest difference was the raising the engine. The next was the fin.

At this point, I had exceeded the performance on my old setup.

Because I can be pretty anal at times (the engineer in me), I sort of got obsessed with this boat tuning thing. So, I added a SS prop from Stiletto which also helped.

Then I researched trim tabs because I wanted to see if I could get even better performance in boat wakes and chop. The Dauntless 15 can be a little on the small side with the large boat wakes and wind driven waves we can get at times. I wanted to see if I could improve this performance - and looked to trim tabs for that.

The tabs make an enormouse difference in the ability to use 'all' of the hull. You can adjust the attitude of the hull to sea and load conditions at will. The guys at Lenco (the tabs I installed) described it as making my 15' boat ride like a 20-22' boat in chop. That exactly describes the change in ride and it is really nice.

The reason no one fools with vertical height adjustment of the engine is that it is a putzy hassle. It takes several hours of fooling around when you'd rather be boating. Dealers don't know anything about it, and in point of fact, would have to observe you using the boat on the water you boat on. That would be prohibitively expensive and difficult. The result is, no one does it. I'm pretty sure people sell boats they are unhappy with for the sole reason that they didn't adjust the motor height - it makes that much difference. It sure did in my case.

So, I'm pretty passionate about this issue. It seems to me to be one of the cosmic truths of small boat set up. I've been around small boats my entire life and I just figured this one out.


Lars Simonsen posted 05-02-2004 09:17 PM ET (US)     Profile for Lars Simonsen  Send Email to Lars Simonsen     
Is the Ventura Hull the same or similar to the 18' Dauntless (many of which also have the "notch" or "pocket")?

I recently put Bennett M-80 trim tabs on my 18' Dauntless, and they made a huge difference in how the hull handles. Previously, my boat got up on plane just fine, but it did have a tendency to ride high in the bow. I raised the motor, and put a whale tail on, and ran it like that for a year or so, and probably would have been satisfied to leave it like that. But I was always a bit dissatisfied with the pounding ride in the chop.

I was itching to try out trim tabs, and finally bought a set after hearing over and over again how much they help the handling of a boat. I quickly realized what an improvement they made in how the boat performs. (I also quickly realized that with trim tabs, the whale tail only creates lots of drag and is unnecessary).

If you have trouble getting (and staying) on plane, the trim tabs will help tremendously. But if that's the only problem you have, the hydrofoil will help you. Where the trim tabs really help is keeping the boat on plane at lower speeds, and allowing you to adjust the attitude of the boat while underway. For example, if you're riding in choppy water, and you have to slow down, your bow will ride high, and you'll have a pounding ride. With the trim tabs, you can hold the bow down, so that you cut through the waves with your bow instead of slamming into the face of each wave with the bottom of the hull. You can therefore maintain a higher speed, and significantly reduce the pounding.

I highly recommend the trim tabs. I paid about $400 for mine, and installed them myself. It was the best $400 I've spent on my boat.


smausert posted 05-03-2004 11:59 AM ET (US)     Profile for smausert  Send Email to smausert     

I am very interested in the installation of the M80s on your Dauntless! The hulls are the same for the year of my Ventura (2001)with the only difference being the inner liner and interior set up. What year is your 18' Dauntless? I believe the hulls are the same beginning in 2000. And the M80s would be a great fit if they work well.

Is your Dauntless really stern heavy? Is the gas tank and oil tank right back there with the outboard? How heavy is your outboard?? Make/Model. How heavy is your boat wet with your usual onboard captain and crew (:)? Is your transom vertical to the keel or did you shim up the tabs to get the tab fins to drop straight into the water as required by Bennett (my Bennett contact is M.J.Thomas). Do you have a few pics....... As you can tell, you may be the person I really needed to hear from. Any info would really be appreciated as I think the boats may be close enough in weight and hulls to really give me insight into whether the M80s will work well. Bennett has suggested the larger M120s or standard 12 by 12 tabs. Further, your description of the problem in chop is a great description of my boat. It comes off plane in a hurry. You got to really be moving for it to stay bow down and on plane but that doesn't work when the chop is up.

Anyway, I would be interested in hearing more about your boat and your installation as a reference. Thanks.

Lars Simonsen posted 05-03-2004 08:21 PM ET (US)     Profile for Lars Simonsen  Send Email to Lars Simonsen     
I'll e-mail you some photos. My gas tank comes within about 14 inches or so of the "notch" in the bottom of the hull (based on my recollection; I didn't go out and measure it). The oil tank is in the back, as is the battery.

I'll send you some photos of the installation.

My boat is a 1998 Dauntless, and the motor is a 1998 Mercury Optimax 135 (fairly heavy, but I don't know the exact weight).

I usually boat with either me an one or two large adults (total of about 675 pounds of human flesh), or with my wife and three sons. I almost always have a full tank, as my gas gage doesn't work, so I always fill the tank back up before using the boat. I think the hull weighs 1800 pounds, motor is probably around 400, a 50 lb (?) battery in the back, 8 pounds of oil in the back, 60 gallons of gas, the stern bench seat in (more weight in the back) maybe 150 pounds of miscellaneous equipment . . . I'll let you total that up . . .

The M-120s would probably be a good choice for your boat. You can't go wrong with bigger tabs (other than finding space to mount them). But there seems to be plenty of space to mount the tabs, even the larger tabs, on the dauntless. I wondered if the M-120s may have been a better choice for my boat, but I'm perfectly satisfied with the M-80s. My transom is vertical to the keel.

From your description of how your boat handles, I think you will benefit greatly from the trim tabs. I like the bennetts very much, and they were easy to install. (Drilling two 3/4 holes in your transom requires some intestinal fortitude, but it's not technically difficult.)

Photos are on the way!


smausert posted 05-04-2004 09:19 PM ET (US)     Profile for smausert  Send Email to smausert     

Thanks for the pictures. They are a great help in getting a feel for this. Based on those pictures I was pretty sure that your Dauntless hull and my Ventura hull were either the same or real close. I wrote to Boston Whaler and my contact there,, wrote back the following:

"Yes, the 1998 18' Dauntless and the 2001 18' Ventura have the same hull. The only difference is the Ventura has a fiberglass topskin added to the hull to give it the bow rider configuration. The hull was completely redesigned in 2002." Using your figures on weight I find that the two configurations are very close in overall weight while underway.

So now I feel much mofe comfortable using your boat and tabs as a benchmark for my Ventura. I will now have to decide whether to go the M-120 or the M-80 route. The M-80 is the easier install; the M-120 will require more effort as a speedo pickup will have to be moved and the tab placement will not be as far outboard as the M-80 due to the stern ladder. Before I make that decision, I am going to try out the Turbo Lift and get a feel for the improvements it makes in my Ventura's performance. Again, I greatly appreciate the help and pics.

Dauntless18 posted 05-05-2004 08:49 PM ET (US)     Profile for Dauntless18    
I also have a 98 Dauntless 18 with Opti 135. My engine is in either the second or third hole down (will check this weekend). I have a significant bow-rise in the hole-shot and then a fair amount of banging on 2-ft chop in LI Sound if I go much faster than barely on a plane (about 2,900 RPM). I have yet to go WOT, as it scares the family too much. Having driven boats occasionally all my life, I know nothing about owning/tinkering with them, but am trying to learn as fast as I can.

I would also like to receive photos of your trim-tabs, as it seems like a good long-term fix (I don't like fixing things twice). BTW, how thick is the back transom hole for the through-fittings and how long did it take you to get over putting the big holes in your boat? :)

Many thanks,

Lars Simonsen posted 05-05-2004 09:10 PM ET (US)     Profile for Lars Simonsen  Send Email to Lars Simonsen     

Is the boat new to you? That may be the biggest problem. But when I moved my motor up to the third hole, I also noticed more bow rise (which was the opposite of what I expected). I put a whale tail on (the quick and cheap fix) and it helped a lot. But it didn't make a tremendous difference on the "pounding" issue. Having now installed the trim tabs, I'd recommend those over a hydrofoil.

Before I installed the trim tabs, it seemed that my boat handled the best if I had two or three of my kids sitting in the bow. I thought about putting a 50 lb sack of sand in my anchor locker!

I also have a very good 19 pitch cupped prop (a three blade Stilleto). That prop gives you a lot of stern lift, and it's a pretty reasonably priced prop.

The trim tabs are a very worthwhile investment. I'll e-mail you my photos.


Wet Foot posted 05-06-2004 10:13 AM ET (US)     Profile for Wet Foot  Send Email to Wet Foot     
Hi Guys,

I'm currently looking at both the older style 18 Dauntless (with the notched bottom) and the newer one (no notch). Does the newer style correct some of the ride issues you have experienced? I also read that the gas tank was moved forward on the newer style; not sure if that is true.

I also have a new Yamaha 8 hp high thrust 4 stroke kicker motor (115 lbs) . I bought that size for the hydraulic tilt. The only main engine light enough to keep transom weight at 510 lbs is the Mercury 125 hp. Should I go over the 510 lbs to get a more powerful Optimax engine, or is the extra weight (80 lbs) not worth it? Can I move rear battery to console storage area?

Dauntless18 posted 05-06-2004 05:54 PM ET (US)     Profile for Dauntless18    
Yes, I bought the boat used (new to me). I too have my family sit up front, which helps, and have also thought about putting a 30 lb. plastic-coated mushroom anchor up there (my idea of a useful version of a sandbag). I have the stainless steel prop that came with the engine, but will look into the prop you mention.

BTW, mine was originally rigged as a fishing boat. I have purchased the Whaler seat pads, but I couldn't bring myself to spring over $500 apiece for each seatback (I have my pride). So, I can get another quality place to make them for much less, but they need the Center-to-center distance between the two tubes of the seatback. If you think of it, I would appreciate that measurement (I think it is between 26.25 and 26.5").

Also, I have to say, I am thrilled with the boat overall. Really great as a family-fun platform and it feels plenty big, even out in the big LI Sound. Of course, I grew up relishing my once-in-a-while trips on my uncle's 1960's 13ft whaler - which I never felt afraid in, by contrast to his 13ft aluminum duck boat from which I have often frantically bailed out water which came in over the bow.

Thanks in advance for the pics.


Lars Simonsen posted 05-06-2004 09:36 PM ET (US)     Profile for Lars Simonsen  Send Email to Lars Simonsen     
David; I'll try to remember to measure the center to center distance between the holes for the seatbacks. Hopefully I'll get a chance to do it tomorrow or this weekend (I'm hoping to get a chance to go fishing!)

Wet foot; I have the 1998 Dauntless, and even with the "notched" hull, I think the hull performs very nicely. It is a little particular about how you have the motor set up (i.e. engine height, pitch and diameter of propellor etc.), but once you've got it "dialed in," it's a wonderful boat. If you don't have trim tabs, you'll at least need a hydrofoil. The trim tabs are vastly more versatile than the hydrofoil, and make a much bigger difference in how the boat handles.

Personally, I wouldn't want anything less powerful than the Optimax 135 on the boat. But I don't know how the power/weight ratio of the 135 compares to the 125. I suspect the 135 is heavier, and that may offset the extra 10 hp (?). But I remember reading somewhere that the 135 Optimax actually produces around 147 hp at the prop, so the power difference may be much larger than 10 hp. I wouldn't want to put a kicker on mine, due to the extra weight. I'm sure that when they filled in the notch, it improved the "stern heaviness" of the hull. On the newer hull (no notch), a kicker may be just fine.

And yes, I think you could install the battery in the console rather than in the rear.


wspellenbe posted 05-07-2004 08:08 AM ET (US)     Profile for wspellenbe  Send Email to wspellenbe     
I have a 1998 Ventura 18 whith a Honda 130 on it. It does have a Bow Trolling motor 36v so there are 3 heavey batteries in the passenger console area. I have never had any problems with the setup and never felt a need for trim tabs or a hydrofoil. Maybe it is the weight up there that fixes any planeing issues. Oh it is one hell of a great family boat.
Use it on a lake and could not have asked for a nicer setup.

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