Front of boat too light? Hard to trim out without getting bounce, 17' Concept...

[White90GT]

I have a 97 Chris Craft Concept 17'. It has a 4.3GL Volvo Penta setup with SX Cobra out drive.

If I'm out alone or with one other person on the passenger side, sometimes I find it difficult to trim the motor up for maximum speed. Take it up much more than all the way down and the boat starts to bounce. Now if I have someone sit up front, I can trim it on up and get more speed out of it.

For now I have a cinder block laying in the very front storage bin wrapped in a heavy quilt for weight. It helps.

I'm wondering if I have some reasonable priced alternatives to help this situation out besides having the weight of a brick sitting up there taking up one of my storage bins (its the anchor storage spot).

I don't know if installing trim tabs would help or maybe one of those whale tail devices for the outdrive.

What are your thoughts?

Here's a couple pics of the boat.

 

[sqbtr]

Re: Front of boat too light? Hard to trim out without getting bounce, 17' Concept...

Nauticus smart tabs

 

[Icyharp]

Re: Front of boat too light? Hard to trim out without getting bounce, 17' Concept...

Nauticus smart tabs

^^^^^Agree^^^^^

 

[LiFeStArTs@FoRtY]

Re: Front of boat too light? Hard to trim out without getting bounce, 17' Concept...

Your boat has a lot of motor both power and weight. I have to agree with above... You're going to need some tabs. Once you have trim tabs, you'll never have a boat with out them.

 

[ezmobee]

Re: Front of boat too light? Hard to trim out without getting bounce, 17' Concept...

At the very least swap out that cinder block with a big water jug or something!

 

[White90GT]

Re: Front of boat too light? Hard to trim out without getting bounce, 17' Concept...

At the very least swap out that cinder block with a big water jug or something!

I've thought about that, but you never know when you might need a cinder block to ditch the old lady. You know, conk her on the head with it, then tie it to her and drown her LOL.

 

[Silver Eagle]

Re: Front of boat too light? Hard to trim out without getting bounce, 17' Concept...

Easy fix , When you start gaining speed use your trim button push it so the out drive is pushing inward from the bottom. This will level the front down and you will even go faster. I used to do that with my old 21 ft Arriva.

 

[Andy'sDelight]

Re: Front of boat too light? Hard to trim out without getting bounce, 17' Concept...

Nauticus smart tabs

^^^^^Agree^^^^^

Disagree. they will help him get on plane faster, but once he's up to speed they are fully retracted in the up position and no longer really doing anything. His problem isn't getting up on plane, it's porpoising once he's up there. His only option is to add weight up front or get controllable trim tabs such as Bennetts.

 

[sqbtr]

Re: Front of boat too light? Hard to trim out without getting bounce, 17' Concept...

Actually I had the porpoising problem with my boat, the tabs completely eliminated it. They are still putting down force when they are deflected.

 

[ufm82]

Re: Front of boat too light? Hard to trim out without getting bounce, 17' Concept...

Incorrect on the trim tab comment- when the tabs are fully deflected upward, they induce less drag but still exert an upward force on the stern, thus stabilizing the bow. The gas shocks on the Smart tabs are always trying to push the tabs back down. When the boat porpoises and the stern angle rises and falls, the shocks compensate for the motion. With that style boat porpoising is common- heavy engine package and light front end. The tabs will do wonders for his issue.

UFM82

 

[Icyharp]

Re: Front of boat too light? Hard to trim out without getting bounce, 17' Concept...

Incorrect on the trim tab comment- when the tabs are fully deflected upward, they induce less drag but still exert an upward force on the stern, thus stabilizing the bow. The gas shocks on the Smart tabs are always trying to push the tabs back down. When the boat porpoises and the stern angle rises and falls, the shocks compensate for the motion. With that style boat porpoising is common- heavy engine package and light front end. The tabs will do wonders for his issue.

UFM82

Thank you, since we just installed a set last week on my buds boat and they do just that, his 18ft'r no longer porpoises. But they again are not for me as I need to be able to control mine more, so enjoy if you go that route.

 

[dockwrecker]

Re: Front of boat too light? Hard to trim out without getting bounce, 17' Concept...

NO STINKIN' FINS! Smart Tabs will fix ya.

 

[tpenfield]

Re: Front of boat too light? Hard to trim out without getting bounce, 17' Concept...

Trim tabs would be fine, but just don't trim up so much when you are boating alone.

 

[White90GT]

Re: Front of boat too light? Hard to trim out without getting bounce, 17' Concept...

Getting up on plane is a slight issue too, again due to the rear being so heavy vs the light front. So if the trim tabs will help both that and the porpoising, I will pick up a set this year.

First I'm having a friend reseal around the transom and inspect things. I have another post in hull repair/rebuild section about that. Outdrive is a little loose on the transom, I think the bolts have stretched over the years and taking some pounding from underwater objects.

 

[smokeonthewater]

Re: Front of boat too light? Hard to trim out without getting bounce, 17' Concept...

Outdrive is a little loose on the transom, I think the bolts have stretched over the years and taking some pounding from underwater objects.

UGH!
the chances of that are VERY slim..... more likely is a partially rotten transom

I sure hope I'm wrong here tho... good luck

 

[White90GT]

Re: Front of boat too light? Hard to trim out without getting bounce, 17' Concept...

Buddy was able to get 1-1/2-2 turns on each of the lower bolts on the mounting brackets inside for the outdrive.

With as much as we jiggled the outdrive around up/down putting pressure, we never saw the surface of the transom either inside or outside move. It was solid. I will take a rubber mallet to it when I get it back in my possession and see if I can hear any sound differences when tapping around the drive.

 

[zopperman]

Re: Front of boat too light? Hard to trim out without getting bounce, 17' Concept...

A rubber mallet isn't a definite indicator. I would take a 3/8 inch drill bit and drill into the transom at 3 points at different heights and check teh quality of the wood shavings. Don't drill through the inner skin... fill it with 3m 5200 marine sealant.. check the shavings. wet and dark = rotten. dry and light = good. A rotten transom can still be sturdy, but it's only a matter of time