On Apr 1, 9:03*am, Tim wrote:
On Apr 1, 6:58*am, anon-e-moose wrote:





Tim wrote:
On Apr 1, 7:11 am, anon-e-moose wrote:
Tim wrote:
On Mar 31, 7:11 pm, Larry wrote:
Tim wrote:
On Mar 30, 6:32 pm, *wrote:
Tim wrote:
On Mar 30, 8:42 am, * *wrote:
* *wrote in message
....
There's an old saying at a local high performance engine shop that
says "Speed costs money, how fast do you want to go?" And I know the
old rule usually applies "you get what you pay for? Well for the few
times I've taken my marquis out it's interesting to get it up on
plane. first , if you ease the throttle, you'll do a wheelie to where
you think the boat will flip over backwards and you do little but plow
water , so you have to nail it and you still get an extreme bow rise
but it settles down and know you're going, but you still have to keep
the RPM up above 2800 or the boat wants to drag back. So I'm
investigating trim tabs. There's all kinds on the market anywhere from
sophisticated hydraulic and independently controlled units ranging up
to around $500.00 all the way down to the spring loaded sets that that
are available for around a hundred bucks. I'm sure that trim tabs
would help the boating experience, but *I'm really wondering how much
trim control I'm actually needing. to make a more efficient ride and
run. I'm constantly accused of being 'tight' but I'm not THAT tight,
because I know that money spent in the right direction will save in
fuel and ride in the longer run. But over kill is still overkill. This
is a 23 ft. V-hull Marquis with a 350 GM engine and not some 3000 hp.
40 ft. Fountain off shore racer. So, anyone have any suggestions?
Tim,
My father had hydraulic trim tabs on his 22 ft. Apollo back in the day, they
were very useful for the application that you are referring. They are also
very helpful if you have an offset in the load, you can equalize easily with
the trim tabs.
For little investment, you might also try one of the following first. *I
have no experience on larger boats, however I know they work well on smaller
run abouts in the 16 to 18 ft. range. There are several other manufactures
on the market besides this one.
http://www.davisnet.com/MARINE/produ...asp?pnum=00448
JT- Hide quoted text -
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Thanks JT. I do have a fin on the lower end, though
Forget the spring -loaded tabs. *They will always add drag.
If your fin is anything like the one I had on my old bowrider, it has an
odd effect on the cornering. *I took mine off.
Try this: *Don't ease the throttle, open it up. *Just as the bow begins
to lower, back off on the throttle until you have it where you want to
be. *If that still takes too long, you can play with prop size, pitch,
cupping and venting. *When you get your desired result, you will may
lose some top end speed. *Prop selection is a PITA for most boat owners..
Larry, that's what I do with my smaller boat and it hole shots quite
well. The big tub? it drags and plows until it decides to get up and
running. I dont' know, maybe I'm asking too much of the take off
performance on the big one, but I don't *think so. Something is amiss
(maybe me!) and I'll have to experiment around with it for a while I
suppose.
Are the carbs clean?
Oh yes. It runs very well. starts easily, and throttles up without a
cough.
I'm sure you have heard the old saw "There's no replacement for
displacement"
If your engine isn't big enough, there is no magic pill to make it
perform like a racehorse.

Also here are some easy checks for performance killers other than trim
and prop sizing. You probably have already checked these items, but just
in case, let's review.

Is the boat waterlogged? Weigh it to find out.

Is there hook or rocker on the boat bottom? A quick eyeball will tell you.

Is there something preventing the throttle plates from opening? Cable
adjustment etc.

Are the secondaries working?

Is static timing somewhere between 6 and 10 degrees?

Does the distributer have mechanical advance? Is it working?

Longshot: Might the coil be breaking down or a plug wire arcing. You
would notice that right away though.

The boat is fine. the engine is fine. The problem is that it doesn't
plane outto what Iwodl expect, but then again, I'm used to a smaller ,
lighter 18ft. craft with a 14 hp 4 cyl engine. Now we're talking about
a high sided heavy, 23 ft small cuddie boat with a 228 hp 350 GM
mercruiser. Sure an elephant isn't going to give stallion performance,
that is if that's what your looking for, but a stallion isn't going to
carry an extra half ton of people and stuff , and give a great ride
with lots of stability either.

the boat does have the performance, it just the planing is a bit of an
issue, and I have no experience with trim tabs but have 'heard' they
can help with performance, planing speed, and economy. That's why all
the questions about them.

One more question. Assuming you can get it to plane, what is the
observed wide open throttle RPM. And please do get the boat weighed
separately from the trailer. Lots of older boats suffer from that malady.- Hide quoted text -

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Once you nail the throttle and the nose shoots for the moon I'd say
you're planing in a few but up to 5 seconds. then the nosed drops down
and you can back to the throttle down to about to 1800 rpm before it
stalls.

Weight the boat seperately woudl really be a chore. aand I dont' know
of any practical way on how to do that around ehre, unless you weighe
the combination, then launched the boat then took the trailer some
where and weighed it seperately. *I believe the hull is in fine shape
thoght at least from what I can tell.- Hide quoted text -

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Yea, I agree. I've always wished I could weigh my trailer boat but it
would be a huge chore.

5 seconds of bow rise is not bad at all for a boat that size. I've
seen some underpowered cruisers that go for like a minute or more with
the bow in the air trying to get on plane. 23' is in range to have a
small block engine and get reasonable performance. Cruising down to
under 2k rpm is pretty durn good as well. The problem is when you get
up to the 27'-29' range and they are still putting a small block in
them to keep the price down.

Those "automatic" tabs and doel fins are generally a disappointment.
If you are going to get tabs, get real operator controlled tabs. But
they will be expensive so make sure you really want them.