Bravo 3 trim modifications ??

[BigDog98]

So I want to bring up a topic that has been brung up plenty of times but still did not answer a few of my questions. Here is my situation. I have a bravo 3 outdrive with dual props at a 22p that reach recommended WOT rpm. First off when I have 5 people on board sitting in the cockpit area , the boat will not plane out without using the trim tabs. Outdrive trim will not plane the boat out. Anyway I recently read up on flipping the trim inserts to the forward position helps with a few things but there is no clarity about it. What exactly does the trim inserts do when flipped in the forward ? Can this little flip help me with planning out with more people? Can it also help me with trying to achieve a higher speed when trimming the drive ? Also with the trim insert flipped in the front position , what would be the trim limit reach measurement ? Would it still be at 21 and 3/4 of an inch as specified in the manual ? Some please help me answer these questions once and for all. Please and thank you.

 

[tpenfield]

Do you have the newer version of the Bravo 3? or is that the original outdrive to the boat? I'm not sure it has the insert, but you can always have a look.

A little more trim 'in' *may* help, but it will not be a game changer.

You see . . . that is a Sea Ray 270 with single big block engine . . . basically a dog. A good friend of mine has one . . . too much boat for a single engine. A friend of his has the twin engine version of the Sea Ray 270 . . . it is like a totally different boat, and in a good way.

The 21-3/4" is a setting that keeps the outdrive within the side restraints on the gimbal ring. So, you might have a 1/2" tweak or so, but keep it at 21-3/4" for safety sake.

 

[alldodge]

Your main issue is there is not enough HP to get you up. Your dry weight list at 7500, so figure full load with folks is 8500 to 9000. When folks are sitting at the stern just makes it worst.

Flipping the insert tucks the drive about a 1/2 inch further under the boat. This may help a tad but also can be dangerous. The B3 turns quicker then a B1, so getting in closer to the stern can also make it turn even faster. This can be violent and can throw people and gear to one side if caught off guard.

Ted has the answer for the trim limit. I'll just add, the limit isn't your issue because you have the drive full down, so your not trimming up.

I had the same issue you have but it was worst. My 27PC comes in dry at 9500 and came with a 7.4 and B3. I had to use the tabs and also get folks to move down into the cabin just to get up on plane. So I changed to a 502 (415HP) and that took care of most the issues, it would still come up slow with folks sitting at the stern, but it worked. So I now have a bored out and built 509 which pushes more the 500 HP. The boat comes right up and no tabs are needed.

In short, you need to rebuild and pull some power out of your 454, or better yet drop in a 502 and you should be fine

 

[BigDog98]

Do you have the newer version of the Bravo 3? or is that the original outdrive to the boat? I'm not sure it has the insert, but you can always have a look.

A little more trim 'in' *may* help, but it will not be a game changer.

You see . . . that is a Sea Ray 270 with single big block engine . . . basically a dog. A good friend of mine has one . . . too much boat for a single engine. A friend of his has the twin engine version of the Sea Ray 270 . . . it is like a totally different boat, and in a good way.

The 21-3/4" is a setting that keeps the outdrive within the side restraints on the gimbal ring. So, you might have a 1/2" tweak or so, but keep it at 21-3/4" for safety sake.

It is the older generation b3 and does have trim inserts. I have a friend with the same boat except he has the front prop a 4 blade and rear is a 3 blade with a 24 pitch setup. He says on gps he gets a top speed at about 38 mph and still get the recommended WOT rpm with 2 adults and 2 small children. He say he has no issues planning what so ever and only uses the outdrive trim. Nothing else.

 

[alldodge]

It is the older generation b3 and does have trim inserts. I have a friend with the same boat except he has the front prop a 4 blade and rear is a 3 blade with a 24 pitch setup. He says on gps he gets a top speed at about 38 mph and still get the recommended WOT rpm with 2 adults and 2 small children. He say he has no issues planning what so ever and only uses the outdrive trim. Nothing else.

If this is the case, then you need to do a compression and leak down test. Your engine is either tired, or your hull is full of water, or your friend has something else going on which is not clear right now. If your friend is reaching WOT with a 24 pitch setup (4 and 3) and you can do the same with 22, there is more investigating needed.

 

[BigDog98]

Your main issue is there is not enough HP to get you up. Your dry weight list at 7500, so figure full load with folks is 8500 to 9000. When folks are sitting at the stern just makes it worst.

Flipping the insert tucks the drive about a 1/2 inch further under the boat. This may help a tad but also can be dangerous. The B3 turns quicker then a B1, so getting in closer to the stern can also make it turn even faster. This can be violent and can throw people and gear to one side if caught off guard.

Ted has the answer for the trim limit. I'll just add, the limit isn't your issue because you have the drive full down, so your not trimming up.

I had the same issue you have but it was worst. My 27PC comes in dry at 9500 and came with a 7.4 and B3. I had to use the tabs and also get folks to move down into the cabin just to get up on plane. So I changed to a 502 (415HP) and that took care of most the issues, it would still come up slow with folks sitting at the stern, but it worked. So I now have a bored out and built 509 which pushes more the 500 HP. The boat comes right up and no tabs are needed.

In short, you need to rebuild and pull some power out of your 454, or better yet drop in a 502 and you should be fine

Your main issue is there is not enough HP to get you up. Your dry weight list at 7500, so figure full load with folks is 8500 to 9000. When folks are sitting at the stern just makes it worst.

Flipping the insert tucks the drive about a 1/2 inch further under the boat. This may help a tad but also can be dangerous. The B3 turns quicker then a B1, so getting in closer to the stern can also make it turn even faster. This can be violent and can throw people and gear to one side if caught off guard.

Ted has the answer for the trim limit. I'll just add, the limit isn't your issue because you have the drive full down, so your not trimming up.

I had the same issue you have but it was worst. My 27PC comes in dry at 9500 and came with a 7.4 and B3. I had to use the tabs and also get folks to move down into the cabin just to get up on plane. So I changed to a 502 (415HP) and that took care of most the issues, it would still come up slow with folks sitting at the stern, but it worked. So I now have a bored out and built 509 which pushes more the 500 HP. The boat comes right up and no tabs are needed.

In short, you need to rebuild and pull some power out of your 454, or better yet drop in a 502 and you should be fine

Here is my whole entire idea behind trim limit. My buddy has the same boat and he is getting much higher top speeds. Now the whole entire 4 x 3 prop setup makes no difference in top speed and the speed issues is another topic that I will get into at a later time. My thinking is that my trim limit is set too high and because of it I am afraid of trimming up when on plane to get the best speed. So I want to know what the trim insert will do for me and what measurement should I set the trim limit at with the trim spacer in the front position to be able to trim all the way up without damaging my u joints and bellows.

 

[BigDog98]

If this is the case, then you need to do a compression and leak down test. Your engine is either tired, or your hull is full of water, or your friend has something else going on which is not clear right now. If your friend is reaching WOT with a 24 pitch setup (4 and 3) and you can do the same with 22, there is more investigating needed.

My compression is good. 160 - 155 in all cylinders with the lowest being 150. I have not done a leak down test but there is one important thing to keep in mind. I am getting recommended WOT rpm, I am getting 4200 - 4400 depending on the day. Just I am getting a top speed of around 33mph meanwhile my friend s doing 38. And I have done research about people who have the same boat and same prop as me and still have higher top speed and cruising speed with the same props as me. So I am starting to think that my trim in not right. Maybe by setting that trim insert forward it will help a bit and by adjusting the trim limit I won't be afraid to trim all the way up.

 

[alldodge]

Your first statement was

the boat will not plane out without using the trim tabs.

So this tells me and my small brain, that your having trouble getting on plane. With five people aboard your having trouble.

My thinking is that my trim limit is set too high and because of it I am afraid of trimming up when on plane to get the best speed. So I want to know what the trim insert will do for me and what measurement should I set the trim limit at with the trim spacer in the front position to be able to trim all the way up without damaging my u joints and bellows.

This comment tells me tells me that you cannot get up to full speed because you cannot get the trim high enough.

I'll say that there is no way that the two issues have anything to do with one another. If your up on plane and you increase more trim then the boat should start to propose (if to high) or plow water (if to low). So if you have trouble getting up, my first guess would be trimming up will cause the rpm to go up but no more speed because it starts to ventilate.

My compression is good. 160 - 155 in all cylinders with the lowest being 150. I have not done a leak down test but there is one important thing to keep in mind. I am getting recommended WOT rpm, I am getting 4200 - 4400 depending on the day. Just I am getting a top speed of around 33mph meanwhile my friend s doing 38. And I have done research about people who have the same boat and same prop as me and still have higher top speed and cruising speed with the same props as me. So I am starting to think that my trim in not right. Maybe by setting that trim insert forward it will help a bit and by adjusting the trim limit I won't be afraid to trim all the way up.

If all this is correct I would suggest taking the boat to a truck stop with a CAT scale and have it weighted. Max rpm should be between 4200 and 4600, so your in the range but there is just to many things which do not add up

 

[BigDog98]

Your first statement was



So this tells me and my small brain, that your having trouble getting on plane. With five people aboard your having trouble.



This comment tells me tells me that you cannot get up to full speed because you cannot get the trim high enough.

I'll say that there is no way that the two issues have anything to do with one another. If your up on plane and you increase more trim then the boat should start to propose (if to high) or plow water (if to low). So if you have trouble getting up, my first guess would be trimming up will cause the rpm to go up but no more speed because it starts to ventilate.



If all this is correct I would suggest taking the boat to a truck stop with a CAT scale and have it weighted. Max rpm should be between 4200 and 4600, so your in the range but there is just to many things which do not add up

I feel that my outdrive trims up too high so I am always afraid of trimming too high and so maybe I am not trimming properly or high enough causing slow speeds. Example ( with just using my trim up button, the drive will go far up enough not to hit a sand bar when beaching without using the trailer button. The 5 people planning issue is different from all this. My boat will plain with 5 or 8 people as long as I deploy my trim tabs into the water causing the bow to stay lower to the water, but from my understanding trim tabs should not be used to plane but rather to level the boat. But since my boat is a little under powered for its size than trim tab need to be used when trying to boat with 5 or more people. However if boating with 2 or 3 people then the boat gets on pane just fine and trim tabs are not needed. But my cruising and top speed is still low from what other people are reporting with 2 or 3 people. My bilge usually has little to no water in the bilge so water in bilge may not be the issue unless my boat has a inner hull that keeps in water that I dont know about and that can only be drained through the garbor plug. Anyhow , my boat has stock props and people with stock props report higher speed than me but i still get the recommended WOT. So I would like to get my outdrive in a little deeper in the water by putting the trim insert forward giving me a better start off trim before adjusting and hope for it to maybe help plane with 5 people a little better.

 

[BigDog98]

Your first statement was



So this tells me and my small brain, that your having trouble getting on plane. With five people aboard your having trouble.



This comment tells me tells me that you cannot get up to full speed because you cannot get the trim high enough.

I'll say that there is no way that the two issues have anything to do with one another. If your up on plane and you increase more trim then the boat should start to propose (if to high) or plow water (if to low). So if you have trouble getting up, my first guess would be trimming up will cause the rpm to go up but no more speed because it starts to ventilate.



If all this is correct I would suggest taking the boat to a truck stop with a CAT scale and have it weighted. Max rpm should be between 4200 and 4600, so your in the range but there is just to many things which do not add up

What would weighing the boat achieve? If my boat was too heavy than i would not get WOT or possibly even plane with 1 or 2 people. Here is my strategy of attack for this upcoming season. Currently my boat is on dry storage for the winter and under shrink wrap so any water inside was drained and dried. Now I will be doing the regular tune up but also replace , plugs,cap n roter,wires,remove the anti siphon,repaint bottom with a more smoother finish paint,run seafoam to clean injectors, clean air intake smooth the rough edges on the prop with a file. Hoping maybe this may help.

 

[alldodge]

Agree in most cases tabs are not used to get up on plane, but when boat is carrying more weight the tabs do work to help get the boat up. There is no issue with this method and as mentioned, this is caused by not having enough power.

Proper trimming for max speed is done in small increments. Bring the drive up higher will hurt once optimum point is reached for a given rpm. Once on plane watch speed and tach. Bump trim up and wait a few seconds, if speed increases, repeat until rpm's increase and speed does not, then tap down to previous position.

A cruiser does not respond like a runabout, at WOT in most cases the drive will need to be brought back down, not up. Again need to watch the tach and speed.

I learned a lot about my cruiser over the past couple years and building the motor. I to use to be at cruise speed and then bring it up to WOT. Watched the rpm come up as I brought the drive up, and speed was just barely increasing. This slight increase was being caused by wind, wave and starting to porpoise.

You have 22 pitch and buddy has 24, if you both have the same drive ratio then there is something wrong IF your tachometer is accurate. Tach's are normally fairly accurate, but some are not.

Your boat could weight more by water being absorbed in the foam which is between the hull and the inner skin. So if your boat was weighted, it would tell you if this was an issue. Mine looked fine until I noticed one small spot at the transom. That small tiny area turned into a transom rebuild, and both water and gas tank replacement.