Low Bow

[kthurm]

I have a 19' Sea Nymph STS190 deckboat. It has a 96" width. I have a 120 Mercury Force on it. Running a 17" prop, and run out about 33 mph maximum. Problem I have is the bow drops quickly when coming up to speed. It does not plow, but water does splash over the sides in 1 foot waves when motoring. Transom height appears correct. I notice the newer deck boats have engine extended back behind the transom about 18 inches. Does this help hold boat bow up at higher speeds? Would a four blade prop help?

 

[crazy charlie]

Re: Low Bow

You need to use the tilt button to change the angle of the motor.Raise it a little at a time and you will see the bow come up a bit with each little bit it raises.Charlie

 

[vipzach]

Re: Low Bow

Crazy is probly right, try raising your trim a little at a time. <br />To answer your question about the 4 blade prop.....no, I don't think that would help.

 

[QC]

Re: Low Bow

Yes, we need to know what you are doing with the trim. Also you should work on moving as much weight aft as possible. This will give the trim much more affect as long as it is not porpoising. On my current boat, before I spent some time moving weight around, it would blow out before full trim. Now I can get the bow up higher.<br /><br />My understanding is that 4 blades WILL increase bow lift. I would post something in the prop section and get some opinions from prop experts on the best design for more bow lift.

 

[kthurm]

Re: Low Bow

You know PTT is so basic I did not even mention that I had already tried the trim and different props. Again, weight shift is a foregone conclusion when experiencing these types of problems. Not a novice, not ignorant, just asking a few questions. I have no experience with jack or extension plates and have not used a four blade prop.

 

[QC]

Re: Low Bow

Sorry it sounded like we were calling you stupid. Stick around and you will understand. Never know what has been done 'til we know . . .<br /><br />BTW, welcome to Iboats. You'll definitely get help here. Look for somethin' from Walleyhed over on the prop forum. Might do a bow lift search too and remember to search in this section too as the prop section is brand new.

 

[kthurm]

Re: Low Bow

Thanks Quietcat, appreciate the feedback. We have a boat shop here and they look like frogs in the headlight when I ask them these types of questions. It is frustrating not to get answers from people who should know. I am really glad to see this forum and the possibility to be able to tap a lot of working knowledge from real experience.

 

[fishingdan]

Re: Low Bow

What happens when you do trim the engine out while running? Does the bow come up at all?

 

[rogerwa]

Re: Low Bow

Could it be a hook in the hull?? How old is boat and have you inspected the keel near the transom to see if it may have developed a hook somehow?? I beleive that would cause an excessive bow down attitude..

 

[QC]

Re: Low Bow

Yeah, I'm with roger. fishingdan too for that matter. Does trim do anything? I'd still think weight too. Batteries? Extra chain? Tools? Maybe as an experiment you should put some extra weight in the stern and just see what happens. How old is this boat?

 

[kthurm]

Re: Low Bow

At low speeds, it has a "decent" amount of lift and can keep the bow at a fairly decent rake. However, any speed above 8 to 10 mph, the nose comes down and trimming has little effect. At flat out (25 to 30 mph) trimming has maybe a six inch rise in response, not much on a 19 foot boat.<br /> The boat is a 1995 model, aluminum hull. Hull is very straight and in great shape, not even a scratch. <br /> Trim is in gtreat shape and works well. Holds when set, no sponge in the hyd. cylinder.<br />Thanks

 

[kthurm]

Re: Low Bow

Have shifted excess weight. Nothing in front, no water in wet well. Boat runs even side to side no listing. All weight moved to back storage, tried it with a mostly empty fuel tank (mid ship 25 gallon)these things are not even noticeable when working with the trim. <br /> I have a friend with a 21 foot fischer deck boat. It is two years old and noticed the motor extension on the back. We talked, and it was a factory design. I thought it was a add-on. I have since viewed others that have the same type extension. Figured there must be a reason they did this on deck boats, trim being the most obvious. <br /> Everything I tried, and the boat just goes flat when running. It is great in smooth water, runs like glass. Not a lot of fun in two foot waves, then I have to plow at low speeds to keep dry and nose up.

 

[QC]

Re: Low Bow

Have you put a straight-edge to the botoom?

 

[kthurm]

Re: Low Bow

Yes, have really checked it over pretty thoroughly. Can seem to find no reason other than my theory of leverage vs. length over the "pivot point" of hull when planing out. <br />Thanks, gotta go for today.

 

[PuddleJumper]

Re: Low Bow

I have a 23 ft deck boat(Bayliner Rendezvous)and trimming up doesn't lift my bow like it does on my bass boat either. I agree with you that it is a function of ratio of overall length vs wide beam.It certainly makes sense that setting the motor back would push bow down and lift the bow.<br />The experts in the prop forum should be able to offer some insight.